ENH: better error message for mis-configured nmake environment

Source/cmEnableLanguageCommand.cxx

@@ -25,9 +25,16 @@ bool cmEnableLanguageCommand
   if(args.size() < 1 )
     {
     this->SetError
-      ("ENABLE_LANGUAGE called with incorrect number of arguments");
+      ("called with incorrect number of arguments");
     return false;
     } 
+  if(this->Makefile->GetCMakeInstance()->GetIsInTryCompile())
+    {
+    this->SetError
+      ("called from a try_compile, "
+       "all languages must be enabled before trying them.");
+    return false;
+    }
   for (std::vector<std::string>::const_iterator it = args.begin();
        it != args.end();
        ++it)