examples: Add hello-rust example.

examples: Add hello-rust example.

* gettext-tools/examples/hello-rust/INSTALL: New file.
* gettext-tools/examples/hello-rust/autogen.sh: New file.
* gettext-tools/examples/hello-rust/autoclean.sh: New file.
* gettext-tools/examples/hello-rust/Cargo.toml.in: New file.
* gettext-tools/examples/hello-rust/src/main.rs.in: New file.
* gettext-tools/examples/hello-rust/Makefile.am: New file.
* gettext-tools/examples/hello-rust/configure.ac: New file.
* gettext-tools/examples/hello-rust/m4/Makefile.am: New file.
* gettext-tools/examples/hello-rust/po/Makefile.am: New file.
* gettext-tools/examples/hello-rust/po/LINGUAS: New file.
* gettext-tools/examples/Makefile.am (EXAMPLESFILES, EXAMPLESDIRS): Add
hello-rust.
* gettext-tools/examples/po/Makefile.am (POTFILES, SMALLPOTS): Update for
hello-rust.
(hello-rust.pot): New target.
(SMALLPOFILES_FOR_lang): Update for hello-rust.
($(srcdir)/../hello-rust/po/$(LL).po): New rule.
* gettext-tools/examples/check-examples (func_check_autoclean_all,
func_check_distclean_all, func_check_maintainerclean_all,
func_check_maintainerclean_vpath_all, func_check_dist_all,
func_check_dist_vpath_all, func_check_install_all, func_check_uninstall_all,
func_check_distcheck_all, func_check_all): Handle hello-rust as well.
(func_check): Add a more useful body.
* gettext-tools/examples/README: Mention hello-rust.
* NEWS: Likewise.