[gegl] png-load: Only print error on error

[Jon Nordby <jonnor src gnome org>]

commit 2d28e773827436b4134bd7fdbe2af521d40d747c
Author: Jon Nordby <jononor gmail com>
Date:   Mon Nov 10 00:50:54 2014 +0100

    png-load: Only print error on error
    
    On EOF read_all() will return FALSE and possibly less-than-requested bytes

 operations/external/png-load.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/operations/external/png-load.c b/operations/external/png-load.c
index f327d9f..eae9aad 100644
--- a/operations/external/png-load.c
+++ b/operations/external/png-load.c
@@ -71,8 +71,8 @@ read_fn(png_structp png_ptr, png_bytep buffer, png_size_t length)
   gsize bytes_read = 0;
   g_assert(stream);
 
-  success = g_input_stream_read_all(stream, buffer, length, &bytes_read, NULL, &err);
-  if (!success) {
+  g_input_stream_read_all(stream, buffer, length, &bytes_read, NULL, &err);
+  if (err) {
     g_printerr("gegl:load-png %s: %s\n", __PRETTY_FUNCTION__, err->message);
   }
 }