qlit: Change compound literals to initializers

The QLIT_QFOO() macros expand into compound literals.  Sadly, gcc
doesn't recognizes these as constant expressions (clang does), which
makes the macros useless for initializing objects with static storage
duration.

There is a gcc bug about it:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71713

Change the macros to expand into initializers.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170825105913.4060-5-marcandre.lureau@redhat.com>
[Commit message improved]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
