Fix PIC relocations for non-Bsymbolic builds

The ARM assembler contains a couple of hand-coded PC relative references
to data defined in other object files. Make sure the externs are tagged
as hidden so the linker knows that it can resolve the reference locally
at build time.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@gmail.com>
Bug: 16853291
Change-Id: I0bd7c7cd9fffa0dfb082f3650da3ad85e4011c49
Merge "Fix PIC relocations for non-Bsymbolic builds"
Revert "Fix build after side-stepping global -Bsymbolic."

This reverts commit 554ffdfb9b4f48733be0d3251d9db15976c61b95.

Bug: 16853291
Merge "Revert "Fix build after side-stepping global -Bsymbolic.""