ld testsuite tidy

ld testsuite tidy

Fixes a few issues:
1) If you use "-fsanitize=address,undefined" in CFLAGS, the Makefile
attempt to trim off -fsanitize options left us with ",undefined".
2) ld_compile adds CFLAGS_FOR_TARGET itself, no need to pass it.
3) CFLAGS might be needed linking bootstrap test.

	* Makefile.am (CFLAGS_FOR_TARGET, CXXFLAGS_FOR_TARGET): Trim off
	all -fsanitize=*.
	* Makefile.in: Regenerate.
	* testsuite/ld-bootstrap/bootstrap.exp: Use CFLAGS when linking.
	* testsuite/ld-cdtest/cdtest.exp: Use CFLAGS_FOR_TARGET when
	linking.
	* testsuite/ld-auto-import/auto-import.exp: Don't pass
	CFLAGS_FOR_TARGET to ld_compile.
	* testsuite/ld-cygwin/exe-export.exp: Likewise.
	* testsuite/ld-elfvers/vers.exp: Likewise.
	* testsuite/ld-elfvsb/elfvsb.exp: Likewise.
	* testsuite/ld-elfweak/elfweak.exp: Likewise.
	* testsuite/ld-gc/gc.exp: Likewise.
	* testsuite/ld-pe/pe-compile.exp: Likewise.
	* testsuite/ld-pe/pe-run.exp: Likewise.
	* testsuite/ld-pe/pe-run2.exp: Likewise.
	* testsuite/ld-plugin/plugin.exp: Likewise.
	* testsuite/ld-shared/shared.exp: Likewise.
	* testsuite/ld-elfcomm/elfcomm.exp: Likewise, and don't allow
	nios2 testing to trash CFLAGS_FOR_TARGET.
	* testsuite/ld-scripts/crossref.exp: Don't pass options in
	CC_FOR_TARGET, do so in CFLAGS_FOR_TARGET instead.
	* testsuite/ld-srec/srec.exp: Likewise, and for CXX.