Preserve addend for R_386_GOT32 and R_X86_64_GOT32

Preserve addend for R_386_GOT32 and R_X86_64_GOT32

We should preserve addend for R_386_GOT32 and R_X86_64_GOT32 as in
"movl $foo@GOT + 4, %eax" and "movq $foo@GOT + 4, %rax".

	PR gas/19600
	* config/tc-i386.c (md_apply_fix): Preserve addend for
	BFD_RELOC_386_GOT32 and BFD_RELOC_X86_64_GOT32.
	* testsuite/gas/i386/addend.d: New file.
	* testsuite/gas/i386/addend.s: Likewise.
	* testsuite/gas/i386/x86-64-addend.d: Likewise.
	* testsuite/gas/i386/x86-64-addend.s: Likewise.
	* testsuite/gas/i386/i386.exp: Run addend and x86-64-addend.
	* testsuite/gas/i386/reloc32.d: Updated.