CMake and Kits: Fix interaction between them

On initial run we offer the user a choice between all the kits, which
are compatible with the cached generator. After the initial run, the
user can't change kits nor generators anymore.
Except if the builds into a new directory or adds a buildconfiguration,
then the user can choose between generators but not kits.

Task-number: QTCREATORBUG-7940
Task-number: QTCREATORBUG-7928

Change-Id: I9b663435cd2e021f7fe08379c1c487a6aebe8976
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: Peter Kümmel <syntheticpp@gmx.net>

src/plugins/projectexplorer/project.cpp

@@ -250,11 +250,21 @@ Target *Project::createTarget(Kit *k)
         return 0;
 
     Target *t = new Target(this, k);
-    t->createDefaultSetup();
-
+    if (!setupTarget(t)) {
+        delete t;
+        return 0;
+    }
     return t;
 }
 
+bool Project::setupTarget(Target *t)
+{
+    t->updateDefaultBuildConfigurations();
+    t->updateDefaultDeployConfigurations();
+    t->updateDefaultRunConfigurations();
+    return true;
+}
+
 Target *Project::restoreTarget(const QVariantMap &data)
 {
     Core::Id id = idFromMap(data);