Ignore warnings from autom4te about Libtool macros. * tests/ltinstloc.test: When testing for presence of warnings, filter out any that are not interesting for this test, e.g., warnings about installed files or about bogusly named cache variables in libtool.m4, emitted by recent Autoconf when older Libtool is used. Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>