Rename asm_out_file function arguments.

As preparation for a new global object that will encapsulate
asm_out_file, we would need to live with a macro that will
define asm_out_file as casm->out_file and thus the name
can't be used in function arguments.

gcc/ChangeLog:

	* config/arm/arm.c (arm_unwind_emit_sequence): Do not declare
	already declared global variable.
	(arm_unwind_emit_set): Use out_file as function argument.
	(arm_unwind_emit): Likewise.
	* config/darwin.c (machopic_output_data_section_indirection): Likewise.
	(machopic_output_stub_indirection): Likewise.
	(machopic_output_indirection): Likewise.
	(machopic_finish): Likewise.
	* config/i386/i386.c (ix86_asm_output_function_label): Likewise.
	* config/i386/winnt.c (i386_pe_seh_unwind_emit): Likewise.
	* config/ia64/ia64.c (process_epilogue): Likewise.
	(process_cfa_adjust_cfa): Likewise.
	(process_cfa_register): Likewise.
	(process_cfa_offset): Likewise.
	(ia64_asm_unwind_emit): Likewise.
	* config/s390/s390.c (s390_asm_output_function_label): Likewise.