x86: Force relocation against local absolute symbol

Define TC_FORCE_RELOCATION_ABS to force relocation against local
absolute symbol.

	PR gas/25756
	* config/tc-i386.h (TC_FORCE_RELOCATION_ABS): New.
	* testsuite/gas/i386/localpic.s: Add a test for relocation
	against local absolute symbol.
	* testsuite/gas/i386/x86-64-localpic.s: Likewise.
	* testsuite/gas/i386/localpic.d: Updated.
	* testsuite/gas/i386/x86-64-localpic.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-localpic.d: Likewise.