cairo_io/cairo-image-surface-xcf.c: Initialize some variables.

These were being warned about in the build.  The functions involved
could potentially finish early without the variables ever being used,
and their cleanups were dependent on their being NULL or not.

Fixes #89

Author: mtwebster

extensions/cairo_io/cairo-image-surface-xcf.c

@@ -581,6 +581,8 @@ _cairo_image_surface_paint_layer (cairo_surface_t *image,
 
 	mask_row = layer->alpha_mask + (y * layer_width) + x;
 
+    rand_gen = NULL;
+
 	if (layer->mode == GIMP_LAYER_MODE_DISSOLVE)
 		rand_gen = g_rand_new_with_seed (DISSOLVE_SEED);
 
@@ -1190,6 +1192,11 @@ _cairo_image_surface_create_from_xcf (GInputStream  *istream,
 
 	performance (DEBUG_INFO, "end init");
 
+    compression = GIMP_COMPRESSION_RLE;
+    layers = NULL;
+    layer_offsets = NULL;
+    colormap = NULL;
+
 	data_stream = g_data_input_stream_new (istream);
 	g_data_input_stream_set_byte_order (data_stream, G_DATA_STREAM_BYTE_ORDER_BIG_ENDIAN);
 
@@ -1230,10 +1237,6 @@ _cairo_image_surface_create_from_xcf (GInputStream  *istream,
 
 	/* properties */
 
-	compression = GIMP_COMPRESSION_RLE;
-	layers = NULL;
-	colormap = NULL;
-
 	read_properties = TRUE;
 	n_properties = 0;
 	while (read_properties) {