clang may produce `movl x@GOTPCREL+4(%rip), %eax` when loading the high 32 bits
of the address of a global variable in -fpic/-fpie mode.
If assembled by GNU as, the fixup emits an R_X86_64_GOTPCRELX with an
addend != -4. The instruction loads from the GOT entry with an offset
and thus it is incorrect to relax the instruction.
If assembled by the integrated assembler, we emit R_X86_64_GOTPCREL for
relocations that definitely cannot be relaxed (D92114), so this patch is not
needed.
This patch disables the relaxation, which is compatible with the implementation in GNU ld
("Add R_X86_64_[REX_]GOTPCRELX support to gas and ld").
Reviewed By: grimar, jhenderson
Differential Revision: https://reviews.llvm.org/D91993
Igor Kudrin