Christophe Giboudeaux authored Apr 27, 2017 and David Faure committed May 05, 2017

Before CMake 3.8, automoc'ed files were saved in the build directory.
With CMake 3.8, they're now saved into $targetName_autogen/include and exported
to $targetName's INCLUDE_DIRECTORIES variable.

mailserializertest.cpp #includes akonadi_serializer_mail.cpp
which #includes moc_akonadi_serializer_mail.cpp.

As a result, CMake had no way to guess where where the automoc'ed file is.

(cherry picked from commit e5c26385)