Partially MFC 7d0c2b1131b68, to enable MAKE_PARAMS per target_arch

This commit made it possible to use different MAKE_PARAMS for each
${target_arch} value, instead of forcing the same MAKE_PARAMS for all of
the ${target_arch} values under one target. I.e, after this you can
build arm.arm with gcc, while building arm.armv6 and arm.armv7 with
clang.

(cherry picked from commit 7d0c2b1131b68f5b120b2df0784cb9da5688f8d9)