* target.h (struct gcc_target): New member external_libcall.
	* target-def.h (TARGET_ASM_EXTERNAL_LIBCALL): Provide default.
	(TARGET_ASM_OUT): Use it.
	* doc/tm.texi (TARGET_ASM_EXTERNAL_LIBCALL): Document.
	* targhooks.c: Convert to ISO C 90.
	(default_external_libcall): New function.
	* targhooks.h (default_external_libcall): Declare.
	* varasm.c (assemble_external_libcall): Use
	targetm.asm_out.external_libcall instead of
	ASM_OUTPUT_EXTERNAL_LIBCALL.
	* config/mips/mips-protos.h [TARGET_IRIX5 || TARGET_IRIX 6]
	(mips_output_external_libcall): Declare.
	* config/mips/mips.c (mips_output_external_libcall): Change
	definition guard.
	Change to match TARGET_ASM_EXTERNAL_LIBCALL.
	Only operate for O32 ABI.
	* config/mips/iris5.h (TARGET_ASM_EXTERNAL_LIBCALL): Define
	instead of ASM_OUTPUT_EXTERNAL_LIBCALL.
	* config/mips/iris6.h (ASM_OUTPUT_EXTERNAL_LIBCALL): Don't undef,
	superceded by TARGET_ASM_EXTERNAL_LIBCALL.

From-SVN: r71689