CMake: Write creators settings into build directory

Write a file qtcsettings.cmake into the build directory. This
file contains all applicable CMake configuration settings that
creator wants to set.

Use "cmake -C qtcsettings.cmake .." to reconfigure on the command
line to make use of this file.

Change-Id: I4a69d082c50bb66e60b4eec1b3155df53e00734d
Reviewed-by: Cristian Adam <cristian.adam@qt.io>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/cmakeprojectmanager/fileapireader.cpp

@@ -131,8 +131,8 @@ void FileApiReader::parse(bool forceCMakeRun, bool forceConfiguration)
     if (forceConfiguration) {
         // Initial create:
         qCDebug(cmakeFileApiMode) << "FileApiReader: Starting CMake with forced configuration.";
-        startCMakeState(
-            CMakeProcess::toArguments(m_parameters.configuration, m_parameters.expander));
+        const FilePath path = m_parameters.buildDirectory.pathAppended("qtcsettings.cmake");
+        startCMakeState(QStringList({QString("-C"), path.toUserOutput()}));
         // Keep m_isParsing enabled!
         return;
     }