config/c6x: Use rtx_insn

config/c6x: Use rtx_insn

gcc/
	* config/c6x/c6x-protos.h (c6x_get_unit_specifier): Strengthen
	param from rtx to rtx_insn *.
	(c6x_final_prescan_insn): Likewise for first param.

	* config/c6x/c6x.c (c6x_current_insn): Likewise for this variable.
	(c6x_output_mi_thunk): Replace use of NULL_RTX with NULL.
	(c6x_expand_compare): Strengthen local "insns" from rtx to
	rtx_insn *.
	(c6x_get_unit_specifier): Likewise for param "insn".
	(c6x_print_unit_specifier_field): Likewise.
	(c6x_final_prescan_insn): Likewise.
	(emit_add_sp_const): Likewise for local "insn".
	(c6x_expand_prologue): Likewise.

From-SVN: r214440