Fix grep portability issues.

Fix grep portability issues.

Grep on Solaris does not support -q.
Reported by Summum Bonum.

	* NEWS: Add a stub for 2.4.2.
	* THANKS: Add Summum Bonum.
	* tests/atlocal.in (EGREP): New.
	(CC, CXX, XSLTPROC): Make it possible to override them via
	envvars.
	* tests/java.at: Use $EGREP instead of egrep.
	Use AT_CHECK's ignore instead of grep's -q.