combo/TARGET_x86*.mk mistakenly added TARGET_GLOBAL_CFLAGS to their
linker command lines. This results in clang builds not working properly,
since they strip some unknown flags from TARGET_GLOBAL_CFLAGS.
Change-Id: I60a1ff5df70305323134435e4ae107ea7acfe8ea
1. Following the setup of gcc in build/core/combo/,
we added the [HOST|TARGET]_<arch>.mk clang config files,
and load only the configs needed by the current product.
2. Added support for the 2nd arch.
Change-Id: I2a383418a9688a050b39492f8e489d40eeeb5f2d
