cmGlobalGenerator: Port Find API to cmMakefile.

Source/cmSetPropertyCommand.cxx

@@ -205,14 +205,8 @@ bool cmSetPropertyCommand::HandleDirectoryMode()
     // The local generators are associated with collapsed paths.
     dir = cmSystemTools::CollapseFullPath(dir);
 
-    // Lookup the generator.
-    if(cmLocalGenerator* lg =
-       this->Makefile->GetGlobalGenerator()->FindLocalGenerator(dir))
-      {
-      // Use the makefile for the directory found.
-      mf = lg->GetMakefile();
-      }
-    else
+    mf = this->Makefile->GetGlobalGenerator()->FindMakefile(dir);
+    if (!mf)
       {
       // Could not find the directory.
       this->SetError