[gegl] Fix newly introduced compile warning

[Martin Nordholts <martinn src gnome org>]

commit 4fed0a26d052d804bc54fb1131313f3d31f19ba4
Author: Martin Nordholts <martinn src gnome org>
Date:   Tue Dec 21 07:55:04 2010 +0100

    Fix newly introduced compile warning
    
    size_t is greater than int on x86_64 (and unsigned). Print it with %lu
    instead of %d so we get rid of the compiler warning.

 operations/external/png-load.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/operations/external/png-load.c b/operations/external/png-load.c
index b0a527f..c7a4c10 100644
--- a/operations/external/png-load.c
+++ b/operations/external/png-load.c
@@ -57,7 +57,7 @@ static FILE * open_png(const gchar *path)
   if((hdr_read_size=fread(header, 1, hdr_size, infile))!=hdr_size)
     {
       fclose(infile);
-      g_warning ("%s is too short for a png file, only %d bytes.",
+      g_warning ("%s is too short for a png file, only %lu bytes.",
 						  path, hdr_read_size);
       return NULL;
     }