that way we don't have to auto-generate code for that in the configures.
note that we now load qt_build_config.prf instead of just qmodule.pri,
which means that exceptions_off is set everywhere. we forcibly re-enable
them for testcases to minimize the deviation from default 3rd party usage.
testlib selftests are not qt testcases, so the one that needs exceptions
needs to enable them explicitly.
Reviewed-by: Joerg Bornemann <email@example.com>
Reviewed-by: Oswald Buddenhagen <firstname.lastname@example.org>