tests: add missing dependency for some 'ar-lib*.test' tests This change fixes spurious failures of the tests ar-lib4.test, ar-lib6a.test and ar-lib6b.test. * tests/Makefile.am (ar-lib4.log): Depend explicitly on the `libtool-macros.log' file. (ar-lib6a.log, ar-lib6b.log): Likewise.