PR gas/977

	PR gas/977
	* config/tc-i386.c (md_estimate_size_before_relax):  Don't relax
	branches to weak symbols.
	(md_apply_fix):  Don't convert fixes against weak symbols to
	section-relative offsets, but save addend for later reloc emission.
	(tc_gen_reloc):  When emitting reloc against weak symbol, adjust
	addend to pre-compensate for bfd_install_relocation.