Properly handle funny file names for headers in config.status.

Properly handle funny file names for headers in config.status.

	The test suite did not cover this bug because the code was not
	quoting properly the arguments of `rm -f' (which "fails" silently)
	as well as the arguments of `diff' (whose output was redirected to
	/dev/null so we couldn't see its error message).
	* lib/autoconf/status.m4 (_AC_OUTPUT_HEADER): Properly quote the
	file names passed to `rm' and `diff'.
	* tests/torture.at (AC_CONFIG_FILES, HEADERS, LINKS and COMMANDS):
	Add a regression test.

Signed-off-by: Benoit Sigoure <tsuna@lrde.epita.fr>
Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>