arc-looping-dash: Add a missing cairo_restore ()

This test called cairo_save () without restoring again. Normally, this doesn't
cause a problem. However, when cairo-test-suite is called with "-a", it also
executes the tests on a similar surface. This then caused
cairo_pop_group_to_source to be called on a cairo_save state which causes a
CAIRO_STATUS_INVALID_RESTORE since commit 5d95ae924e.

Signed-off-by: Uli Schlachter <psychon@znc.in>

test/arc-looping-dash.c

@@ -66,6 +66,8 @@ draw (cairo_t *cr, int width, int height)
     cairo_set_dash (cr, dashes, 2, 0);
     cairo_stroke (cr);
 
+    cairo_restore (cr);
+
     return CAIRO_TEST_SUCCESS;
 }