Upstream priorizes freeimage in general, but nsgif supports animated
gif while freeimage displays them as a static image. This allows setting
USE=freeimage while still getting animations if (optional) USE=gif.
--- a/src/main.c
+++ b/src/main.c
@@ -20,2 +20,6 @@
 
+#ifdef IMV_BACKEND_LIBNSGIF
+  imv_install_backend(imv, &imv_backend_libnsgif);
+#endif
+
 #ifdef IMV_BACKEND_FREEIMAGE
@@ -39,6 +43,2 @@
 #endif
-
-#ifdef IMV_BACKEND_LIBNSGIF
-  imv_install_backend(imv, &imv_backend_libnsgif);
-#endif