QmakeProjectManager: Don't add mkspec include dir explicitly

It will be added via INCLUDE anyway.

This also removes all code using BaseQtVersion::systemHeaderPaths(),
which is thus also removed. This function was introduced to support
Symbian.

Change-Id: Id372e1cfc20bd22de948ed9a7d28dfa9135cbfa9
Task-number: QTCREATORBUG-13964
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/plugins/qmakeprojectmanager/qmakeproject.cpp

@@ -507,22 +507,9 @@ void QmakeProject::updateCppCodeModel()
         // part->defines
         templatePart->projectDefines += pro->cxxDefines();
 
-        // part->headerPaths
-        if (qtVersion) {
-            foreach (const HeaderPath &header, qtVersion->systemHeaderPathes(k)) {
-                ProjectPart::HeaderPath::Type type = ProjectPart::HeaderPath::IncludePath;
-                if (header.kind() == HeaderPath::FrameworkHeaderPath)
-                    type = ProjectPart::HeaderPath::FrameworkPath;
-                templatePart->headerPaths += ProjectPart::HeaderPath(header.path(), type);
-            }
-        }
-
         foreach (const QString &inc, pro->variableValue(IncludePathVar)) {
             const auto headerPath
                 = ProjectPart::HeaderPath(inc, ProjectPart::HeaderPath::IncludePath);
-            // We've added header paths from qtVersion->systemHeaderPathes() above,
-            // which also contains the mkspecs dir. However, it's also part of
-            // the pro->variableValue(IncludePathVar), so check for duplicates.
             if (!templatePart->headerPaths.contains(headerPath))
                 templatePart->headerPaths += headerPath;
         }

src/plugins/qtsupport/baseqtversion.cpp

@@ -1183,14 +1183,6 @@ MacroExpander *BaseQtVersion::macroExpander() const
     return &m_expander;
 }
 
-QList<HeaderPath> BaseQtVersion::systemHeaderPathes(const Kit *k) const
-{
-    Q_UNUSED(k);
-    QList<HeaderPath> result;
-    result.append(HeaderPath(mkspecPath().toString(), HeaderPath::GlobalHeaderPath));
-    return result;
-}
-
 void BaseQtVersion::addToEnvironment(const Kit *k, Environment &env) const
 {
     Q_UNUSED(k);

src/plugins/qtsupport/baseqtversion.h

@@ -146,7 +146,6 @@ public:
     bool hasDemos() const;
     QString demosPath() const;
 
-    virtual QList<ProjectExplorer::HeaderPath> systemHeaderPathes(const ProjectExplorer::Kit *k) const;
     virtual QString frameworkInstallPath() const;
 
     // former local functions