Fix makedepend depmode for VPATH builds. * lib/depcomp [makedepend]: Remove any VPATH prefix from the object file name, so a rebuild doesn't attempt to update the .Po files in the source tree. * tests/depcomp9.test: New test. * tests/Makefile.am (TESTS): Update. * NEWS: Update. Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>