examples: Rename gnome3 XML files shorter than 99
* gettext-tools/examples/hello-c-gnome3/hello.gresource.xml: Rename
from org.gnu.gettext.examples.hello.gresource.xml.
* gettext-tools/examples/hello-c-gnome3/hello-gschema.xml: Rename
from org.gnu.gettext.examples.hello.gschema.xml.
* gettext-tools/examples/hello-c-gnome3/po/POTFILES.in: Adjust the
file name change.
* gettext-tools/examples/hello-c-gnome3/po/Makefile.am: Adjust the
file name change.
* gettext-tools/examples/Makefile.am: Adjust the file name change.
* gettext-tools/examples/po/Makefile.am: Adjust the file name change.
