Provide an option for the base/rom extension that causes the toolchain id (ARMCC or GCCE) to be defined for the C preprocessor phase of rombuild, enabling rom files to be conditionally included or excluded depending on whether the toolchain can build them. This mimics the same change for Beagleboard.

z:
cd test
rem runtests e32test.auto.bat
rem format c:
rem runtests f32test.auto.bat -d c