Reject the dysfunctional gettext in Solaris libc, other than Solaris 11.4.

Reject the dysfunctional gettext in Solaris libc, other than Solaris 11.4.

This fixes a 'make installcheck' failure.

<https://www.illumos.org/issues/13423> has been reported more than 4 years ago.
I don't have hope that they will fix it, ever.

* gettext-runtime/m4/gettext.m4 (AM_GNU_GETTEXT): On Solaris other than
Solaris 11.4, don't use the gettext() function in libc.
* gettext-tools/tests/init.cfg (prepare_locale_): Remove function.
* gettext-tools/tests/format-c-3: Remove prepare_locale_ invocations.
* gettext-tools/tests/format-c-4: Likewise.
* gettext-tools/tests/format-c-5: Likewise.
* gettext-tools/tests/intl-0: Likewise.
* gettext-tools/tests/intl-1: Likewise.
* gettext-tools/tests/intl-2: Likewise.
* gettext-tools/tests/intl-3: Likewise.
* gettext-tools/tests/intl-4: Likewise.
* gettext-tools/tests/intl-6: Likewise.
* gettext-tools/tests/intl-7: Likewise.
* gettext-tools/tests/intl-thread-1: Likewise.
* gettext-tools/tests/intl-thread-2: Likewise.
* gettext-tools/tests/intl-thread-3: Likewise.
* gettext-tools/tests/lang-bash: Likewise.
* gettext-tools/tests/lang-c: Likewise.
* gettext-tools/tests/lang-c++: Likewise.
* gettext-tools/tests/lang-c++20: Likewise.
* gettext-tools/tests/lang-c++26: Likewise.
* gettext-tools/tests/lang-clisp: Likewise.
* gettext-tools/tests/lang-csharp: Likewise.
* gettext-tools/tests/lang-d: Likewise.
* gettext-tools/tests/lang-gawk: Likewise.
* gettext-tools/tests/lang-go: Likewise.
* gettext-tools/tests/lang-guile: Likewise.
* gettext-tools/tests/lang-java: Likewise.
* gettext-tools/tests/lang-javascript: Likewise.
* gettext-tools/tests/lang-librep: Likewise.
* gettext-tools/tests/lang-lua: Likewise.
* gettext-tools/tests/lang-modula2: Likewise.
* gettext-tools/tests/lang-objc: Likewise.
* gettext-tools/tests/lang-pascal: Likewise.
* gettext-tools/tests/lang-perl-1: Likewise.
* gettext-tools/tests/lang-perl-2: Likewise.
* gettext-tools/tests/lang-php: Likewise.
* gettext-tools/tests/lang-python-1: Likewise.
* gettext-tools/tests/lang-python-2: Likewise.
* gettext-tools/tests/lang-ruby: Likewise.
* gettext-tools/tests/lang-rust: Likewise.
* gettext-tools/tests/lang-sh: Likewise.
* gettext-tools/tests/lang-smalltalk: Likewise.
* gettext-tools/tests/lang-tcl: Likewise.
* gettext-tools/tests/lang-vala: Likewise.
* gettext-tools/tests/msgfmt-20: Likewise.
* gettext-tools/tests/plural-1: Likewise.
* NEWS: Mention the change.