Compiler warnings on Windows


git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@914 632fc199-4ca6-4c93-a231-07263d6284db
diff --git a/jdatadst.c b/jdatadst.c
index ff87ecd..b3fdd3e 100644
--- a/jdatadst.c
+++ b/jdatadst.c
@@ -191,7 +191,7 @@
   my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
 
   *dest->outbuffer = dest->buffer;
-  *dest->outsize = dest->bufsize - dest->pub.free_in_buffer;
+  *dest->outsize = (unsigned long)(dest->bufsize - dest->pub.free_in_buffer);
 }
 #endif