plug-ins: Add loop count to GIF parasite

In ccd12318, the parasite to remember if the GIF was an animation
did not actually store the number of loops. This patch fixes that.

plug-ins/common/file-gif-load.c

@@ -600,6 +600,7 @@ load_image (GFile     *file,
           GimpParasite *parasite;
           gchar        *str;
 
+          str = g_strdup_printf ("%d", Gif89.num_loops);
           parasite = gimp_parasite_new ("gif/animated",
                                         GIMP_PARASITE_PERSISTENT,
                                         strlen (str) + 1,