re PR target/37170 (gcc.dg/weak/weak-1.c)

re PR target/37170 (gcc.dg/weak/weak-1.c)

	PR middle-end/37170
	PR middle-end/37280
	* final.c (mark_symbol_ref_as_used): New helper function.
	(output_operand): Instead of just looking inside MEMs for
	SYMBOL_REFs, use new helper function and for_each_rtx.
	* varasm.c (assemble_external): Move #ifndef ASM_OUTPUT_EXTERNAL
	to after weak-handling.  Don't mark decls with TREE_STATIC as weak.
	Make head comment more general.
	* config/darwin.c (machopic_output_indirection): Handle weak
	references here, like in assemble_external.

From-SVN: r140539