arc: Remove Rcq constraint.

arc: Remove Rcq constraint.

gcc/
	* config/arc/arc.cc (arc_check_short_reg_p): New function.
	(arc_address_cost): Replace satisfies_constraint_Rcq with the
	above new function.
	(arc_output_addsi): Likewise.
	(split_addsi): Likewise.
	(split_subsi): Likewise.
	* config/arc/arc.md (movqi_insn): Remove Rcq constraint.
	(movhi_insn): Likewise.
	(movsi_insn): Likewise.
	(tst_movb): Likewise.
	(tst): Likewise.
	(tst_bitfield): Likewise.
	(abssi2): Likewise.
	(addsi3_mixed): Likewise.
	(mulhisi3_reg): Likewise.
	(umulhisi3_reg): Likewise.
	(mulsi_600): Likewise.
	(mul64): Likewise.
	(subsi3_insn): Likewise.
	(bicsi3_insn): Likewise.
	(xorsi3): Likewise.
	(negsi2): Likewise.
	(one_cmplsi2): Likewise.
	(lshrsi3_insn): Likewise.
	(cmpsi_cc_insn_mixed): Likewise.
	(cmpsi_cc_zn_insn): Likewise.
	(btst): Likewise.
	(cmpsi_cc_z_insn): Likewise.
	(cmpsi_cc_c_insn): Likewise.
	(indirect_jump): Likewise.
	(casesi_jump): Likewise.
	(call_i): Likewise.
	(call_value_i): Likewise.
	(bbit): Likewise.
	(abssf2): Likewise.
	(ashlsi2_cnt1): Likewise.
	(lshrsi3_cnt1): Likewise.
	(ashrsi3_cnt1): Likewise.
	* config/arc/constraints.md (Rcq): Remove.

Signed-off-by: Claudiu Zissulescu <claziss@gmail.com>