[Gold,x86_64] Convert mov foo@GOTPCREL(%rip), %reg to lea foo(%rip), %reg

[Gold,x86_64] Convert mov foo@GOTPCREL(%rip), %reg to lea foo(%rip), %reg

2015-04-06  Ilya Tocar  <ilya.tocar@intel.com>

	PR gold/17641
	* x86_64.cc (Target_x86_64::can_convert_mov_to_lea): New.
	(Target_x86_64::Scan::local): Don't create GOT entry, when we
	can convert mov to lea.
	(Target_x86_64::Scan::global): Ditto.
	(Target_x86_64::Relocate::relocate): Convert mov foo@GOTPCREL(%rip),
	%reg to lea foo(%rip), %reg if possible.
	* testsuite/Makefile.am (x86_64_mov_to_lea): New test.
	* testsuite/x86_64_mov_to_lea1.s: New.
	* testsuite/x86_64_mov_to_lea2.s: Ditto.
	* testsuite/x86_64_mov_to_lea3.s: Ditto.
	* testsuite/x86_64_mov_to_lea4.s: Ditto.
	* testsuite/x86_64_mov_to_lea.sh: Ditto.
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