libtextstyle: Omit tests that rely on more than the public libtextstyle API.
* libtextstyle/autogen.sh: Don't pass --with-tests to gnulib-tool.
(GNULIB_MODULES): Add term-ostream-tests.
* gnulib-local/modules/term-ostream-tests (Makefile.am): Don't add
@INTL_MACOSX_LIBS@ to test_term_ostream_LDADD.
* gettext-tools/gnulib-tests/Makefile.am (test_term_ostream_LDADD): Add
@INTL_MACOSX_LIBS@ here.
