...for the code model parts and declare 5.0 as the supported version for
the clang static analyzer.

Adapt versions and tests, remove code assuming clang <= 5.0.

LLVM/Clang 5 was released on 07 Sep 2017.

Task-number: QTCREATORBUG-18931
Task-number: QTCREATORBUG-18657
Task-number: QTCREATORBUG-17187
Task-number: QTCREATORBUG-14881
Change-Id: I53b00258ca06a1d2e57f9379dacc54b310687295
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>