Fixes for ARC STAR 9000593624

In gas:

2013-02-19  Claudiu Zissulescu <claudiu.zissulescu@synopsys.com>

	ARC STAR 9000593624

	* config/tc-arc.c (md_assemble): Hack for cases when st or ld
	needs a shimm fixup.

In ld:

2013-02-19  Claudiu Zissulescu <claudiu.zissulescu@synopsys.com>

	ARC STAR 9000593624

	* arc-opc-old.c (OFFSET_AC): Use ARC_OPERAND_SIGNED, not
	ARC_OPERAND_LIMM.