Fix a print format warning

Change-Id: I30a6a9835073a7c0f5751fc34aed958c91a050ee
Author: Edwin Vane <edwin.vane@intel.com>
Reviewed-by: Tareq A Siraj <tareq.a.siraj@intel.com>
diff --git a/libzipfile/centraldir.c b/libzipfile/centraldir.c
index 0e264a3..911e2b9 100644
--- a/libzipfile/centraldir.c
+++ b/libzipfile/centraldir.c
@@ -192,7 +192,7 @@
 

     // too small to be a ZIP archive?

     if (bufsize < EOCD_LEN) {

-        fprintf(stderr, "Length is %d -- too small\n", bufsize);

+        fprintf(stderr, "Length is %zd -- too small\n", bufsize);

         goto bail;

     }