Enable clang for init, after fix of global .mk files.

LOCAL_FORCE_STATIC_EXECUTABLE was not working properly for clang
because -Bstatic was ignored by clang. We can now enable clang
for init after the -static flag is added to link static executable
files in build/core/definitions.mk.

BUG: 18008984
Change-Id: I3f361b83c1e0b313914603dff33fd090cd3b116a