shared: add ColorItem from Gravity screensaver.

* A useful utility class that will also be used by Terminal later

Change-Id: I23020a401fbab7d4116df31f965ae61ecaf2a6cd

configure & build: Rework legacy GCC detection to parse versions outside of Jam.

Jam comparison logic is string-based, and so was detecting GCC >= 10
as being < 2. This rectifies that by removing the GCC version parsing
from Jam logic entirely, and setting various BuildConfig variables
instead.

Change-Id: I0c0ae3b9002fb5e77f9ca7a78600c91871657f03
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3293
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

Gravity: Add ColorItem and RainbowItem

instead of using boring StringItems

ColorItem draws a small colored rectangle left of the string
RainbowItem draws a rainbow colored rectangle left of the string

Gravity: spaces => tabs in Jamfile

Use libstdc++, libsupc++ and libgcc from gcc_syslibs.

* Instead of faking libstdc++.so from libstdc++.a, use libstdc++.so
from the gcc_syslibs build feature for everything except x86_gcc2.
* Use libgcc_s.so from the gcc_syslibs build feature for everything but
x86_gcc2 (which still carries libgcc as part of libroot.so).
* Drop filtering of libgcc objects for libroot, as that is no longer
necessary since we're only using libgcc-as-single-object for libroot
with x86_gcc2, where the filtered object file doesn't exist. Should
the objects that used to be filtered cause any problems as part of
libgcc_s.so, we can always filter them as part of the gcc build.
* Use libsupc++.so from the gcc_syslibs build feature for everything but
x86_gcc2.
* Adjust all Jamfiles accordingly.
* Deactivate building of faked libstdc++.so for non-x86-gcc2. For
x86_gcc2, we still build libstdc++.so from the sources in the Haiku
source tree as part of the Haiku build .
* Put gcc_syslibs package onto the image, when needed.

GL: Remove OpenGL kit, x86 Mesa

* Depend on Mesa packages to provide functionality

More work towards hybrid support

* All packaging architecture dependent variables do now have a
respective suffix and are set up for each configured packaging
architecture, save for the kernel and boot loader variables, which
are still only set up for the primary architecture.
For convenience TARGET_PACKAGING_ARCH, TARGET_ARCH, TARGET_LIBSUPC++,
and TARGET_LIBSTDC++ are set to the respective values for the primary
packaging architecture by default.
* Introduce a set of MultiArch* rules to help with building targets for
multiple packaging architectures. Generally the respective targets are
(additionally) gristed with the packaging architecture. For libraries
the additional grist is usually omitted for the primary architecture
(e.g. libroot.so and <x86>libroot.so for x86_gcc2/x86 hybrid), so that
Jamfiles for targets built only for the primary architecture don't
need to be changed.
* Add multi-arch build support for all targets needed for the stage 1
cross devel package as well as for libbe (untested).

Update glu and mesa package

Also use the new build feature rules.

Gravity: Big code changes

* Reworked code style completely.
* Improved the behaviour of the particles.
* Made particles smaller (2,5x performance gain).
* Cleaned unnecessary includes.
* Tried improving performance with glCallList - performance dropped even more.
* Tried improving performance with glDrawArrays - no noticeable performance changes.

Gravity: Disable warnings for gcc2 build.

gravity: Fix path in Jamfile. Fix build

screensaver: Add gravity based on GCI 2012 work

* A modified version of TriEdgeAI's original work.
* Cleaned up style problems
* Some virtual functions didn't mesh properly with
ones defined in the OpenGL kit (Draw for example)
* Wrote Jamfile
* Add missing include cstdlib for rand
* Not in image yet as it still needs gcc2 testing

Use libstdc++, libsupc++ and libgcc from gcc_syslibs.

* Instead of faking libstdc++.so from libstdc++.a, use libstdc++.so
from the gcc_syslibs build feature for everything except x86_gcc2.
* Use libgcc_s.so from the gcc_syslibs build feature for everything but
x86_gcc2 (which still carries libgcc as part of libroot.so).
* Drop filtering of libgcc objects for libroot, as that is no longer
necessary since we're only using libgcc-as-single-object for libroot
with x86_gcc2, where the filtered object file doesn't exist. Should
the objects that used to be filtered cause any problems as part of
libgcc_s.so, we can always filter them as part of the gcc build.
* Use libsupc++.so from the gcc_syslibs build feature for everything but
x86_gcc2.
* Adjust all Jamfiles accordingly.
* Deactivate building of faked libstdc++.so for non-x86-gcc2. For
x86_gcc2, we still build libstdc++.so from the sources in the Haiku
source tree as part of the Haiku build .
* Put gcc_syslibs package onto the image, when needed.

GL: Remove OpenGL kit, x86 Mesa

* Depend on Mesa packages to provide functionality

More work towards hybrid support

* All packaging architecture dependent variables do now have a
respective suffix and are set up for each configured packaging
architecture, save for the kernel and boot loader variables, which
are still only set up for the primary architecture.
For convenience TARGET_PACKAGING_ARCH, TARGET_ARCH, TARGET_LIBSUPC++,
and TARGET_LIBSTDC++ are set to the respective values for the primary
packaging architecture by default.
* Introduce a set of MultiArch* rules to help with building targets for
multiple packaging architectures. Generally the respective targets are
(additionally) gristed with the packaging architecture. For libraries
the additional grist is usually omitted for the primary architecture
(e.g. libroot.so and <x86>libroot.so for x86_gcc2/x86 hybrid), so that
Jamfiles for targets built only for the primary architecture don't
need to be changed.
* Add multi-arch build support for all targets needed for the stage 1
cross devel package as well as for libbe (untested).

Update glu and mesa package

Also use the new build feature rules.

Gravity: Big code changes

* Reworked code style completely.
* Improved the behaviour of the particles.
* Made particles smaller (2,5x performance gain).
* Cleaned unnecessary includes.
* Tried improving performance with glCallList - performance dropped even more.
* Tried improving performance with glDrawArrays - no noticeable performance changes.

Gravity: Disable warnings for gcc2 build.

gravity: Fix path in Jamfile. Fix build

screensaver: Add gravity based on GCI 2012 work

* A modified version of TriEdgeAI's original work.
* Cleaned up style problems
* Some virtual functions didn't mesh properly with
ones defined in the OpenGL kit (Draw for example)
* Wrote Jamfile
* Add missing include cstdlib for rand
* Not in image yet as it still needs gcc2 testing