util_win32: add missing valname param to query_val function

mercurial/util_win32.py

@@ -202,7 +202,7 b' def lookup_reg(key, valname=None, scope='
     except ImportError:
         return None
 
-    def query_val(scope, key):
+    def query_val(scope, key, valname):
         try:
             keyhandle = OpenKey(scope, key)
             return QueryValueEx(keyhandle, valname)[0]