configure: give check_for() the ability to test several item types at once

Currently, check_for() can only test one of prog, inc or lib at once. This patch
removes this limitation.

Signed-off-by: "Benoît THÉBAUDEAU" <benoit.thebaudeau@advansee.com>

 reporter_name="Alexander BIGGA"

 reporter_url="http://sourceware.org/ml/crossgcc/2008-06/msg00031.html"

 reporter_comment=""