cmake: Fix directory used to find the cache

The start and home directories are the same, but the intent of the
code here is to use what is currently called the HomeOutput directory.

Source/cmake.cxx

@@ -1189,7 +1189,7 @@ int cmake::HandleDeleteCacheVariables(const std::string& var)
     }
 
   // remove the cache
-  this->CacheManager->DeleteCache(this->GetStartOutputDirectory());
+  this->CacheManager->DeleteCache(this->GetHomeOutputDirectory());
   // load the empty cache
   this->LoadCache();
   // restore the changed compilers