BaseTools: remove ARMGCC and ARMLINUXGCC toolchains

BaseTools: remove ARMGCC and ARMLINUXGCC toolchains

The ARMGCC and ARMLINUXGCC toolchains are specific to the ARM and
AARCH64 architectures, and overlap with the toolchain configuration
that is provided by the GCC44 - GCC49 toolchains, which are defined
for all architectures.

To reduce the maintenance burden, and make it easier to keep these
different architectures aligned, remove the ARMGCC and ARMLINUXGCC
toolchains entirely.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18212 6f19259b-4bc3-4df7-8a09-765794883524