ProjectPart: save codegen flags in project part

And add them to other clang code model arguments.
These flags provide architecture for cross-compilation
when ios kit is selected.

Task-number: QTCREATORBUG-19437
Task-number: QTCREATORBUG-19430
Change-Id: I7a485f49d637371bb28b2096086d7d8a4b0c404a
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/cpptools/projectpart.h

@@ -140,6 +140,7 @@ public:
     ProjectExplorer::Macros toolChainMacros;
     ToolChainWordWidth toolChainWordWidth = WordWidth32Bit;
     QString toolChainTargetTriple;
+    QStringList extraCodeModelFlags;
     BuildTargetType buildTargetType = Unknown;
 };