BuildConfiguration: Introduce signal buildTypeChanged()

Needed by android plugin.

Change-Id: I46543d4889e0e740697439e18e9c1ea0d3fef222
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: BogDan Vatra <bogdan@kde.org>

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.h

@@ -61,6 +61,8 @@ public:
     bool useNinja() const;
     void setUseNinja(bool);
 
+    void emitBuildTypeChanged();
+
 signals:
     void useNinjaChanged(bool);