sys/resource.h: add rusage compatibility fields, set to zero

POSIX defines this structure but specifies only two fields (which we
already implement). However, both the *BSD and Linux have agreed on
some more fields, which are often assumed to be there by applications.

The benefice of having compatibility fields is
greater as having to patch every other software at HaikuPorts.

Change-Id: Ie28ca2e348aa16b4c57eb3498eb62175100d9b9d
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4083
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Niels Sascha Reedijk <niels.reedijk@gmail.com>
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

Introduce __set_errno() throughout libroot.

* add errno_private.h, which defines the __set_errno() macro with
and without tracing
* instead of setting errno manually, all libroot's code now invokes
__set_errno(), which makes it much easier to trace changes to errno
* redirect glibc's use of __set_errno() to our own version

Renamed src/kernel to src/system.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12359 a95241bf-73f2-0310-859d-f6bbb57e9c96

Introduce __set_errno() throughout libroot.

* add errno_private.h, which defines the __set_errno() macro with
and without tracing
* instead of setting errno manually, all libroot's code now invokes
__set_errno(), which makes it much easier to trace changes to errno
* redirect glibc's use of __set_errno() to our own version

Renamed src/kernel to src/system.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12359 a95241bf-73f2-0310-859d-f6bbb57e9c96