Re-land r337333, "Teach Clang to emit address-significance tables.",
which was reverted in r337336.
The problem that required a revert was fixed in r337338.
Also added a missing "REQUIRES: x86-registered-target" to one of
Original commit message:
Teach Clang to emit address-significance tables.
By default, we emit an address-significance table on all ELF
targets when the integrated assembler is enabled. The emission of an
address-significance table can be controlled with the -faddrsig and
Differential Revision: https://reviews.llvm.org/D48155