[PATCH v2] gas: Enable PC-relative diff relocations on sparc64

[Jose E. Marchesi]

    gas/
    	* config/tc-sparc.c (tc_gen_reloc): Convert BFD_RELOC_8/16/32/64
    	into the corresponding BFD_RELOC_8/16/32/64_PCREL relocation
    	when requested.
    	* config/tc-sparc.h (DIFF_EXPR_OK): Define to enable PC-relative
    	diff relocations.
    	(TC_FORCE_RELOCATION_SUB_LOCAL): Define to ensure only supported
    	relocations are made PC-relative.
    	(CFI_DIFF_EXPR_OK): Define to 0 to force BFD_RELOC_32_PCREL to
    	be used directly, since otherwise BFD_RELOC_SPARC_UA32 will be
    	used for .eh_frame which cannot in general be converted to a
    	BFD_RELOC_32_PCREL due to alignment requirements.

Applied in master.
Thanks!