[ARC] Fix assembler relaxation.

[ARC] Fix assembler relaxation.

Fix assembler relaxation step for add, ld, mov, mpy and sub
instructions. Add tests to it.

gas/
2017-02-15  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/tc-arc.c (md_convert_frag): Remove @pcl relocation
	information from input expression.
	(assemble_insn): Make sure pcrel is correctly set.
	(arc_pcrel_adjust): Compensate for PCL rounding.
	* testsuite/gas/arc/relax-add01.d: New file.
	* testsuite/gas/arc/relax-add01.s: Likewise.
	* testsuite/gas/arc/relax-add02.d: Likewise.
	* testsuite/gas/arc/relax-add02.s: Likewise.
	* testsuite/gas/arc/relax-add03.d: Likewise.
	* testsuite/gas/arc/relax-add03.s: Likewise.
	* testsuite/gas/arc/relax-add04.d: Likewise.
	* testsuite/gas/arc/relax-add04.s: Likewise.
	* testsuite/gas/arc/relax-ld01.d: Likewise.
	* testsuite/gas/arc/relax-ld01.s: Likewise.
	* testsuite/gas/arc/relax-ld02.d: Likewise.
	* testsuite/gas/arc/relax-ld02.s: Likewise.
	* testsuite/gas/arc/relax-mov01.d: Likewise.
	* testsuite/gas/arc/relax-mov01.s: Likewise.
	* testsuite/gas/arc/relax-mov02.d: Likewise.
	* testsuite/gas/arc/relax-mov02.s: Likewise.
	* testsuite/gas/arc/relax-mpy01.d: Likewise.
	* testsuite/gas/arc/relax-mpy01.s: Likewise.
	* testsuite/gas/arc/relax-sub01.d: Likewise.
	* testsuite/gas/arc/relax-sub01.s: Likewise.
	* testsuite/gas/arc/relax-sub02.d: Likewise.
	* testsuite/gas/arc/relax-sub02.s: Likewise.
	* testsuite/gas/arc/relax-sub03.d: Likewise.
	* testsuite/gas/arc/relax-sub03.s: Likewise.
	* testsuite/gas/arc/relax-sub04.d: Likewise.
	* testsuite/gas/arc/relax-sub04.s: Likewise.

opcodes/
2017-02-15  Claudiu Zissulescu  <claziss@synopsys.com>

	* arc-opc.c (UIMM6_20R): Define.
	(SIMM12_20): Use above.
	(SIMM12_20R): Define.
	(SIMM3_5_S): Use above.
	(UIMM7_A32_11R_S): Define.
	(UIMM7_9_S): Use above.
	(UIMM3_13R_S): Define.
	(SIMM11_A32_7_S): Use above.
	(SIMM9_8R): Define.
	(UIMM10_A32_8_S): Use above.
	(UIMM8_8R_S): Define.
	(W6): Use above.
	(arc_relax_opcodes): Use all above defines.