Fix compiler warnings.

FossilOrigin-Name: 5e30c6ea707f9d381127e8b2bb59e0b39bc00997da2c14d32a0e302d0121203b

ext/misc/zipfile.c

@@ -2170,6 +2170,10 @@ static int zipfileRegister(sqlite3 *db){
     zipfileRollback,           /* xRollback */
     zipfileFindFunction,       /* xFindMethod */
     0,                         /* xRename */
+    0,                         /* xSavepoint */
+    0,                         /* xRelease */
+    0,                         /* xRollback */
+    0                          /* xShadowName */
   };
 
   int rc = sqlite3_create_module(db, "zipfile"  , &zipfileModule, 0);