initialize static buffer with 0's

ext/exif/exif.c

@@ -2785,6 +2785,7 @@ static int exif_process_IFD_TAG(image_info_type *ImageInfo, char *dir_entry, cha
 				// pointers read without the need to free them
 				// explicitley before returning.
 				*/
+				memset(&cbuf, 0, sizeof(cbuf));
 				value_ptr = cbuf;
 			}