ASM_OUTPUT_DEF isn't defined for TARGET_MACHO.  Use ASM_OUTPUT_LABEL to
generate the __x86_return_thunk label, instead of the set directive.
Update testcase to remove the __x86_return_thunk label check.  Since
-fno-pic is ignored on Darwin, update testcases to scan or "push" only
on Linux.

gcc/

	PR target/83839
	* config/i386/i386.c (output_indirect_thunk_function): Use
	ASM_OUTPUT_LABEL, instead of ASM_OUTPUT_DEF, for TARGET_MACHO
	for  __x86_return_thunk.

gcc/testsuite/

	PR target/83839
	* gcc.target/i386/indirect-thunk-1.c: Scan for "push" only on
	Linux.
	* gcc.target/i386/indirect-thunk-2.c: Likewise.
	* gcc.target/i386/indirect-thunk-3.c: Likewise.
	* gcc.target/i386/indirect-thunk-4.c: Likewise.
	* gcc.target/i386/indirect-thunk-7.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-1.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-2.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-5.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-6.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-7.c: Likewise.
	* gcc.target/i386/indirect-thunk-extern-1.c: Likewise.
	* gcc.target/i386/indirect-thunk-extern-2.c: Likewise.
	* gcc.target/i386/indirect-thunk-extern-3.c: Likewise.
	* gcc.target/i386/indirect-thunk-extern-4.c: Likewise.
	* gcc.target/i386/indirect-thunk-extern-7.c: Likewise.
	* gcc.target/i386/indirect-thunk-register-1.c: Likewise.
	* gcc.target/i386/indirect-thunk-register-3.c: Likewise.
	* gcc.target/i386/indirect-thunk-register-4.c: Likewise.
	* gcc.target/i386/ret-thunk-10.c: Likewise.
	* gcc.target/i386/ret-thunk-11.c: Likewise.
	* gcc.target/i386/ret-thunk-12.c: Likewise.
	* gcc.target/i386/ret-thunk-13.c: Likewise.
	* gcc.target/i386/ret-thunk-14.c: Likewise.
	* gcc.target/i386/ret-thunk-15.c: Likewise.
	* gcc.target/i386/ret-thunk-9.c: Don't check the
	__x86_return_thunk label.
	Scan for "push" only for Linux.

From-SVN: r256704