Sometimes a test's main() function recognizes that the environment
does not support the test, and therefore exits.  In this case, we
still should run g_test_run() so that a TAP harness will print the
test plan ("1..0") and the test will be marked as skipped.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1543513531-1151-2-git-send-email-pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>