Add support for ARC instruction relaxation in the assembler.

Add support for ARC instruction relaxation in the assembler.

gas/
2016-01-26  Claudiu Zissulescu  <claziss@synopsys.com>
	    Janek van Oirschot <jvanoirs@synopsys.com>

        * config/tc-arc.h (TC_FRAG_TYPE, TC_PCREL_ADJUST, MAX_INSN_ARGS)
        (MAX_INSN_FLGS, MAX_FLAG_NAME_LENGHT, TC_GENERIC_RELAX_TABLE):
        Define.
        (arc_flags, arc_relax_type): New structure.
        * config/tc-arc.c (FRAG_MAX_GROWTH, RELAX_TABLE_ENTRY)
	(RELAX_TABLE_ENTRY_MAX): New define.
        (relaxation_state, md_relax_table, arc_relaxable_insns)
	(arc_num_relaxable_ins): New variable.
	(rlx_operand_type, arc_rlx_types): New enums.
	(arc_relaxable_ins): New structure.
        (OPTION_RELAX): New option.
        (arc_insn): New relax member.
        (arc_flags): Remove.
        (relax_insn_p): New function.
        (apply_fixups): Likewise.
        (relaxable_operand): Likewise.
        (may_relax_expr): Likewise.
        (relaxable_flag): Likewise.
        (arc_pcrel_adjust): Likewise.
        (md_estimate_size_before_relax): Implement.
        (md_convert_frag): Likewise.
        (md_parse_option): Handle new mrelax option.
        (md_show_usage): Likewise.
        (assemble_insn): Set relax member.
        (emit_insn0): New function.
        (emit_insn1): Likewise.
        (emit_insn): Handle relaxation case.
	* NEWS: Mention the new relaxation option.
	* doc/c-arc.texi (ARC Options): Document new mrelax option.

gas/testsuite
2016-01-26  Claudiu Zissulescu  <claziss@synopsys.com>

        * gas/arc/relax-avoid1.d: New file.
        * gas/arc/relax-avoid1.s: Likewise.
        * gas/arc/relax-avoid2.d: Likewise.
        * gas/arc/relax-avoid2.s: Likewise.
        * gas/arc/relax-avoid3.d: Likewise.
        * gas/arc/relax-avoid3.s: Likewise.
	* gas/arc/relax-b.d: Likewise.
        * gas/arc/relax-b.s: Likewise.

include/opcode/
2016-01-26  Claudiu Zissulescu  <claziss@synopsys.com>
	    Janek van Oirschot  <jvanoirs@synopsys.com>

        * arc.h (arc_opcode arc_relax_opcodes, arc_num_relax_opcodes):
        Declare.

opcodes/
2016-01-26  Claudiu Zissulescu  <claziss@synopsys.com>
	    Janek van Oirschot  <jvanoirs@synopsys.com>

        * arc-opc.c (arc_relax_opcodes, arc_num_relax_opcodes): New
        variable.