Output parsers: Replace the chaining approach

Use "flat" aggregation instead.
This is another step towards the formatter/parser merger.
Along the way, also fix some some subclasses (mostly in BareMetal) that
erroneously forwarded handled output to other parsers.

Task-number: QTCREATORBUG-22665
Change-Id: I12947349ca663d2e6bbfc99efd069d69e2b54969
Reviewed-by: hjk <hjk@qt.io>

src/plugins/qmakeprojectmanager/qmakeparser.h

@@ -41,7 +41,7 @@ public:
     QMakeParser();
 
 private:
-    void handleLine(const QString &line, Utils::OutputFormat type) override;
+    Status doHandleLine(const QString &line, Utils::OutputFormat type) override;
 
     QRegExp m_error;
 };