Optimize branches to non-weak symbols with visibility

Optimize branches to non-weak symbols with visibility

Branches to global non-weak symbols defined in the same segment with
non-default visibility can be optimized the same way as branches to
local symbols.

gas/

	* config/tc-i386.c (elf_symbol_resolved_in_segment_p): New.
	(md_estimate_size_before_relax): Use it.

gas/testsuite/

	* gas/i386/i386.exp: Run relax-3 and x86-64-relax-2.
	* gas/i386/relax-3.d: New file.
	* gas/i386/relax-3.s: Likewise.
	* gas/i386/x86-64-relax-2.d: Likewise.