Enable safe ICF with LLD.

Support for safe ICF was added to LLD in LLVM r337429. This reduces
the size of sailfish system.img by 7.6MB.

The address-significance tables created by Clang to support LLD's
implementation of safe ICF are incompatible with ld -r. Therefore we
need to pass -fno-addrsig to the compiler to prevent it from creating
an address-significance table when building a cc_object.

Change-Id: I83e28741e6b3cdf09566447d2658ce48594f2074