ld: Skip some x86 ifunc tests for lynxos and nto

ld: Skip some x86 ifunc tests for lynxos and nto

On lynxos and nto:

regexp_diff match failure
regexp "^Relocation section '.rel(a|).plt' at offset 0x[0-9a-f]+ contains 1 entry:$"
line   "Relocation section '.rel.dyn' at offset 0x74 contains 1 entry:"
FAIL: ld-ifunc/ifunc-23a-x86

	* testsuite/ld-ifunc/ifunc-23a-x86.d: Skip *-*-lynxos *-*-nto*.
	* testsuite/ld-ifunc/ifunc-24a-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-25a-x86.d: Likewise.