Issue #29338: Don't output an empty signature for class constructor.

Author: serhiy-storchaka

Lib/pydoc.py

@@ -917,7 +917,7 @@ def spilldata(msg, attrs, predicate):
             signature = None
         if signature:
             argspec = str(signature)
-            if argspec:
+            if argspec and argspec != '()':
                 decl = name + self.escape(argspec) + '\n\n'
 
         doc = getdoc(object)
@@ -1236,7 +1236,7 @@ def makename(c, m=object.__module__):
             signature = None
         if signature:
             argspec = str(signature)
-            if argspec:
+            if argspec and argspec != '()':
                 push(name + argspec + '\n')
 
         doc = getdoc(object)