Drop unused variables and lambda captures

Also, add context to connect() expressions where we are or were
capturing "this".

Change-Id: I6e006ba6f83d532478018550d148ee93eca59605
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>
Reviewed-by: hjk <hjk@qt.io>

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.cpp

@@ -277,7 +277,7 @@ QList<ConfigModel::DataItem> CMakeBuildConfiguration::completeCMakeConfiguration
         return QList<ConfigModel::DataItem>();
 
     return Utils::transform(m_buildDirManager->parsedConfiguration(),
-                            [this](const CMakeConfigItem &i) {
+                            [](const CMakeConfigItem &i) {
         ConfigModel::DataItem j;
         j.key = QString::fromUtf8(i.key);
         j.value = QString::fromUtf8(i.value);