Use LOCAL_POST_LINK_CMD to insert the objcopy command for linker.

Previously we duplicated code in build/core/executable.mk and it's hard
to maintain. LOCAL_POST_LINK_CMD is a clean solution for this.

Bug: 17403674
Change-Id: I8c054bf782af68cf1f88b8d787a78ca74a7968b5
2 files changed