gl: Fix bug in _cairo_gl_pattern_texture_setup()

The memory allocated to "image" at line 298 is not freed before moving to label fail at line 305 and 314.
This patch takes care of this memory leak in above mentioned cases.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=91537
Signed-off-by: Sahil Vij <sahil.vij@samsung.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>

src/cairo-gl-operand.c

@@ -301,17 +301,21 @@ _cairo_gl_pattern_texture_setup (cairo_gl_operand_t *operand,
        so we need to release this device while we paint it to the image. */
     if (src_is_gl_surface) {
 	status = _cairo_gl_context_release (ctx, status);
-	if (unlikely (status))
+	if (unlikely (status)) {
+	    _cairo_surface_unmap_image (&surface->base, image);
 	    goto fail;
+	}
     }
 
     status = _cairo_surface_offset_paint (&image->base, extents->x, extents->y,
 					  CAIRO_OPERATOR_SOURCE, _src, NULL);
 
     if (src_is_gl_surface) {
 	status = _cairo_gl_context_acquire (dst->base.device, &ctx);
-	if (unlikely (status))
+	if (unlikely (status)) {
+	    _cairo_surface_unmap_image (&surface->base, image);
 	    goto fail;
+	}
     }
 
     status = _cairo_surface_unmap_image (&surface->base, image);