ProjectExplorer: Fix release build

And compile on macOS. Amends c15e09e0fe.

Change-Id: I39395f341e8590104dd96348aa8fc12d437dbd28
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/projectexplorer/customparser.cpp

@@ -26,6 +26,7 @@
 #include "customparser.h"
 
 #include "projectexplorerconstants.h"
+#include "projectexplorer.h"
 #include "task.h"
 
 #include <coreplugin/icore.h>
@@ -677,8 +678,8 @@ void ProjectExplorerPlugin::testCustomOutputParsers()
                           outputLines);
 }
 
-} // namespace ProjectExplorer
-
 #endif
 
+} // namespace ProjectExplorer
+
 #include <customparser.moc>