Fix some mingw test failures.
* gettext-tools/tests/intl-1: Ignore different end-of-line convention in the
output.
* gettext-tools/tests/intl-2: Likewise.
* gettext-tools/tests/intl-3: Likewise.
* gettext-tools/tests/msgfmt-desktop-1: Likewise.
* gettext-tools/tests/msgfmt-desktop-2: Likewise.
* gettext-tools/tests/sentence-1: Likewise.
* gettext-tools/tests/cldr-plurals-1: Likewise.
* gettext-tools/tests/lang-c: On native Windows, ignore different end-of-line
convention in the output.
* gettext-tools/tests/lang-c++: Likewise.
* gettext-tools/tests/msgfilter-8: On native Windows, use sh, not /bin/sh.
