C++: Remove unneeded qualifications

Mostly done using the following ruby script:
Dir.glob('**/*.cpp').each { |file|
  next if file =~ %r{src/shared/qbs|/qmljs/}
  s = File.read(file)
  s.scan(/^using namespace (.*);$/) {
    ns = $1
    t = s.gsub(/^(.*)\b#{ns}::((?!Const)[A-Z])/) { |m|
      before = $1
      char = $2
      if before =~ /"|\/\/|\\|using|SIGNAL|SLOT|Q_/
        m
      else
        before + char
      end
    }
    if t != s
      puts file
      File.open(file, 'w').write(t)
    end
  }
}

Change-Id: I6fbe13ddc1485efe95c3156097bf41d90c0febac
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/plugins/cppeditor/cppuseselectionsupdater.cpp

@@ -360,7 +360,7 @@ void CppUseSelectionsUpdater::handleSymbolCaseAsynchronously(const Document::Ptr
 void CppUseSelectionsUpdater::handleSymbolCaseSynchronously(const Document::Ptr document,
                                                             const Snapshot &snapshot)
 {
-    const CPlusPlus::Document::Ptr previousDocument = m_document;
+    const Document::Ptr previousDocument = m_document;
     m_document = document;
 
     const Params params = Params(m_editorWidget->textCursor(), document, snapshot);