[build] Rename x86 project to "x64"

Build output will now be in build-x64 instead of build-x86
Renamed and updated various scripts as appropriate

Within zircon, $ARCH remains "x86".
This avoids having to rename kernel/arch/x86/ and change a lot of #include paths
Removed unnecessary $SUBARCH build variable

Renamed the kernel target from pc-x86 to pc, and the board name in boards.list
from "x86" to "pc".

Change-Id: I0eb44a21ba731653b92f3ce2b78a7819c0a8f61c

[build] re-enable sysroot which was accidentally disabled

Change-Id: I0a0397bd6d5f637ba4b2479fcefc19a2121246a6

[ddk][device] deprecate iotxn_queue op and device_iotxn_queue()

Most of this noise is due to various drivers that were not including
assert.h or limits.h (for PAGE_SIZE) or driver.h, instead counting on
getting them indirectly via iotxn.h via driver.h

Change-Id: Ib9d0cd56a2b81f45887e1eeb79c22b3fc44d72da

[style] Fix spelling of veneer in top-level makefile

Change-Id: I2f1861a8d8dcabb9c46e85a8c35be0ce2592f04e

[build] Simplify target ("project") names

The only projects supported now are Zircon, so having "zircon-"
at the front of every name is just more typing. There is only
one architecture associated with each platform name, and for
x86-64 there is only one platform. The old -> new mappings are:

zircon-pc-x86-64 -> x86
zircon-qemu-arm64 -> arm64
zircon-gauss-arm64 -> gauss
zircon-hikey960-arm64 -> hikey960
zircon-odroidc2-arm64 -> odroidc2

The old project names continue to work as aliases during
a transition period but they are deprecated.

Since all projects are Zircon (nee Magenta), the -m switch to
buildall is removed and the build-all-zircon script is deprecated.

Change-Id: Icf88e93b460df053be251c88d9dffd8c6da82518

[make] fix a problem with top level phony rules

The wrapper makefile has been eating phony rules since forever, pass
them through to the second make instantiation.
Rename the 'kern' rule to 'kernel', which now fully works.

Change-Id: I8cdebd7ae70d7620bb2d1913a257c74e980b4b23

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[build] flatten the build

Previously we treated kernel/, system/, and third_party/ as
overlays on a shared namespace. This required the concept
of "canonical" module names, and a lot of complexity to ensure
that things didn't collide and the build worked.

This change gets rid of that, no longer passes -I to make,
so that include directives from our *.mk files do not magically
wildcard across various paths, etc.

The most user-visible change is that everywhere where a module
name is specified (MODULE_DEPS, MODULE_LIBS, etc), full module
names like kernel/lib/io or system/ulib/mxio must be used instead
of previously-allowed "short" names like lib/io and ulib/mxio.

The build output still has a similar shape, but the first segment
of the module path (kernel/, system/, or third_party/) is no
longer elided under $(BUILDDIR)

Change-Id: I525aba1da1c86eb7a86007bddc669f7eeebfedd5

[build] allow sysroot directory to be specified with BUILDSYSROOT

Also make always-included build output a little terser.

Change-Id: I698fae7cfaec47f284d1a8db95bac767c82120c1

[make] Avoid overriding makefile's defaults in engine.mk

kernel/engine.mk was (unintentionally) overriding the some of default
values for variables with explicit defaults set in the root makefile.
To fix, explicitly export the defaulted values from the top-level
makefile.

Change-Id: Ia2dd2ca0e364f850e83c7ce4bccb417d9d4ca637

[makefile] Flip ENABLE_BUILD_SYSROOT's default to true

Change-Id: I3ea179775a73c902a52376af75b45a84c0d46127

[build] unify x86-64 builds under magenta-pc-x86-64

Fold the magenta-pc-uefi and magenta-qemu-x86-64 builds into a
unified magenta-pc-x86-64 build. The pc-x86-64 build enabled an
intel-hda driver, while the pc-uefi driver had some workarounds
for Pixel2 (gated on recognition of the Pixel2 via ACPI).

Update the default project and the run-magenta script.

Change-Id: Iff2c3f347b342d056296eb0625c635a82a67d978

[make] squelch the size spew if ENABLE_BUILD_LISTFILES isn't set

-Switch ENABLE_BUILD_LISTFILES and friends to use the TOBOOL macro to
be slightly friendlier to users.
-Squelch the entering/exiting make debug lines

Change-Id: If710bb81d4b95c37e9b14749eb50dbf8709f74c0

[build] feature-ize listing files and sysroot generation

ENABLE_BUILD_LISTFILES must be "true" to generat listings,
dumps, symbols dumps, etc.

ENABLE_BUILD_SYSROOT must be "true" to generate the sysroot
and build artifacts

Change-Id: I72b6e26bd791a5231e1fa1a55ff465a3079c160a

Make BUILDROOT overridable in root makefile

Change-Id: I3773aafa1a38b6eb2a3111cf819569a4b80b9d7a

[magenta] Initial commit