intltool fails to extract comments from glade-type files when not last attributes

[Claude Paroz]

If you have some element with a comments not at the last position, intltool fails to extract the comment.

Work:
<property name="label" translatable="yes" context="infinitive" comments="my comment">

Fail:
<property name="label" translatable="yes" comments="my comment" context="infinitive">

For example, just swap the translatable and comments properties in tests/cases/extract8.glade and the test will fail.

[Данило Шеган (danilo)]

I believe we should just fall back on the native xgettext glade support, which seems to work correctly. The one difference I see is that intltool currently keeps the newlines in XML attributes, whereas xgettext -L glade doesn't. I don't think this is a big deal.

[Данило Шеган (danilo)]

Except that gtkbuilder files context is not supported :(

[Данило Шеган (danilo)]

Upstream gettext bugs that are blocking this: https://savannah.gnu.org/bugs/index.php?34506 and https://savannah.gnu.org/bugs/index.php?29216