fix Cppyy::GetMethodSignature to return list of argument type

Author: Vipul-Cariappa

clingwrapper/src/clingwrapper.cxx

@@ -1413,7 +1413,16 @@ std::string Cppyy::GetMethodArgDefault(TCppMethod_t method, TCppIndex_t iarg)
 std::string Cppyy::GetMethodSignature(TCppMethod_t method, bool show_formal_args, TCppIndex_t max_args)
 {
   // FIXME : Doesn't work for template functions as it does in cling
-  return Cpp::GetFunctionSignature(method);
+  std::ostringstream sig;
+  sig << "(";
+  size_t args = Cpp::GetFunctionNumArgs(method);
+  for (size_t i = 0; i < args; i++) {
+    sig << Cppyy::GetMethodArgTypeAsString(method, i);
+    if (i != args -1)
+      sig << ", ";
+  }
+  sig << ")";
+  return sig.str();
 }
 
 std::string Cppyy::GetMethodPrototype(TCppMethod_t method, bool show_formal_args)