Correctly set compression specific general purpose bit flags.
diff --git a/lib/zip.h b/lib/zip.h
index abdaf07..dd8afe8 100644
--- a/lib/zip.h
+++ b/lib/zip.h
@@ -226,7 +226,8 @@
     ZIP_SOURCE_SEEK_WRITE,      /* set position for writing */
     ZIP_SOURCE_TELL_WRITE,      /* get write position */
     ZIP_SOURCE_SUPPORTS,        /* check whether source supports command */
-    ZIP_SOURCE_REMOVE           /* remove file */
+    ZIP_SOURCE_REMOVE,          /* remove file */
+    ZIP_SOURCE_GET_COMPRESSION_FLAGS	/* set version needed and compression flags, internal only */
 };
 typedef enum zip_source_cmd zip_source_cmd_t;