Add -mrelax-relocations= to x86 assembler

Add -mrelax-relocations= to x86 assembler

The x86 relax relocations introduced in binutils 2.26 aren't supported
by linker on Solaris older than Solaris 12.  To use x86 assembler with
older Solaris linker, this patch adds

1. A command line option -mrelax-relocations= to x86 assembler to
control whether to generate relax relocations.
2. A configure option --enable-x86-relax-relocations to decide whether
x86 assembler should generate relax relocations by default.  It is
defaulted to yes, except for x86 Solaris targets older than Solaris 12.

gas/

	PR gas/19520
	* NEWS: Mention new command line option -mrelax-relocations and
	new configure option --enable-x86-relax-relocations for x86
	target.
	* config.in: Regenerated.
	* configure.ac: Add --enable-x86-relax-relocations.
	(ac_default_x86_relax_relocations): New.  Default to 1 except
	for x86 Solaris targets older than Solaris 12.
	(DEFAULT_GENERATE_X86_RELAX_RELOCATIONS): Define.
	* configure: Likewise.
	* config/tc-i386.c (generate_relax_relocations): New.
	(OPTION_MRELAX_RELOCATIONS): Likewise.
	(output_disp): Don't generate relax relocations if
	generate_relax_relocations is 0.
	(md_longopts): Add -mrelax-relocations.
	(md_show_usage): Likewise.
	(md_parse_option): Handle OPTION_MRELAX_RELOCATIONS.
	* doc/c-i386.texi: Document -mrelax-relocations=.
	* testsuite/gas/i386/got-no-relax.d: New file.
	* testsuite/gas/i386/x86-64-gotpcrel-no-relax.d: Likewise.
	* testsuite/gas/i386/got.d: Pass -mrelax-relocations=yes to as.
	* testsuite/gas/i386/localpic.d: Likewise.
	* testsuite/gas/i386/mixed-mode-reloc32.d: Likewise.
	* testsuite/gas/i386/reloc32.d: Likewise.
	* testsuite/gas/i386/x86-64-gotpcrel.d: Likewise.
	* testsuite/gas/i386/x86-64-localpic.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-gotpcrel.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-localpic.d: Likewise.
	* testsuite/gas/i386/i386.exp: Run got-no-relax and
	x86-64-gotpcrel-no-relax.

ld/

	PR gas/19520
	* testsuite/ld-i386/branch1.d: Pass -mrelax-relocations=yes to as.
	* testsuite/ld-i386/call1.d: Likewise.
	* testsuite/ld-i386/call2.d: Likewise.
	* testsuite/ld-i386/call3a.d: Likewise.
	* testsuite/ld-i386/call3b.d: Likewise.
	* testsuite/ld-i386/call3c.d: Likewise.
	* testsuite/ld-i386/call3d.d: Likewise.
	* testsuite/ld-i386/call3e.d: Likewise.
	* testsuite/ld-i386/call3f.d: Likewise.
	* testsuite/ld-i386/call3g.d: Likewise.
	* testsuite/ld-i386/call3h.d: Likewise.
	* testsuite/ld-i386/jmp1.d: Likewise.
	* testsuite/ld-i386/jmp2.d: Likewise.
	* testsuite/ld-i386/lea1c.d: Likewise.
	* testsuite/ld-i386/load1.d: Likewise.
	* testsuite/ld-i386/load2.d: Likewise.
	* testsuite/ld-i386/load3.d: Likewise.
	* testsuite/ld-i386/load4a.d: Likewise.
	* testsuite/ld-i386/load5a.d: Likewise.
	* testsuite/ld-i386/mov2b.d: Likewise.
	* testsuite/ld-i386/mov3.d: Likewise.
	* testsuite/ld-ifunc/ifunc-21-x86-64.d: Likewise.
	* testsuite/ld-ifunc/ifunc-22-x86-64.d: Likewise.
	* testsuite/ld-ifunc/ifunc-5r-local-x86-64.d: Likewise.
	* testsuite/ld-x86-64/call1a.d: Likewise.
	* testsuite/ld-x86-64/call1b.d: Likewise.
	* testsuite/ld-x86-64/call1c.d: Likewise.
	* testsuite/ld-x86-64/call1d.d: Likewise.
	* testsuite/ld-x86-64/call1e.d: Likewise.
	* testsuite/ld-x86-64/call1f.d: Likewise.
	* testsuite/ld-x86-64/call1h.d: Likewise.
	* testsuite/ld-x86-64/call1i.d: Likewise.
	* testsuite/ld-x86-64/load1a.d: Likewise.
	* testsuite/ld-x86-64/load1b.d: Likewise.
	* testsuite/ld-i386/got1a.S: Load GOT into %ecx and use it.
	* testsuite/ld-i386/got1.dd: Updated.
	* testsuite/ld-i386/got1d.S (1): Removed.
	* testsuite/ld-i386/i386.exp: Add -Wa,-mrelax-relocations=yes.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.