ProjectExplorer: Give build systems a name

... and make it accessible through a variable.

Fixes: QTCREATORBUG-26147
Change-Id: I0601c09a74360b91fe8421876207a8f4ae9d75b6
Reviewed-by: hjk <hjk@qt.io>

src/plugins/autotoolsprojectmanager/autotoolsbuildsystem.h

@@ -44,6 +44,7 @@ public:
 
 private:
     void triggerParsing() final;
+    QString name() const final { return QLatin1String("autotools"); }
 
     /**
      * Is invoked when the makefile parsing by m_makefileParserThread has