CMakeProjectManager: Provide way for plugins to autodetect cmake tools

This patch adds support for plugins to register a callback/lambda
to autodetect CMakeTools that would not be found by the default auto-
detection function. Without this feature the CMakeToolManager would
drop autodetected CMakeTools otherwise on every start.

Change-Id: I23b146e5b9acc60018ac87ea4b6cc7573fa0dd30
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>

src/plugins/cmakeprojectmanager/cmakeprojectplugin.cpp

@@ -73,7 +73,6 @@ bool CMakeProjectPlugin::initialize(const QStringList & /*arguments*/, QString *
     addAutoReleasedObject(new CMakeLocatorFilter);
 
     new CMakeToolManager(this);
-    CMakeToolManager::restoreCMakeTools();
 
     ProjectExplorer::KitManager::registerKitInformation(new CMakeKitInformation);
 
@@ -82,4 +81,6 @@ bool CMakeProjectPlugin::initialize(const QStringList & /*arguments*/, QString *
 
 void CMakeProjectPlugin::extensionsInitialized()
 {
+    //restore the cmake tools before loading the kits
+    CMakeToolManager::restoreCMakeTools();
 }