This is similar to and extends the prevention of thread cancellation
introduced by commit ba05af82d3. This
prevents the situation in which a signal gets delivered (usually because
of a crash) and the parent process' handler is run, doing things it
shouldn't between vfork() and execve().
Most C libraries (all that I've investigated) unblock SIGABRT on
abort(), so this doesn't affect them. Likewise, on most OSes, crashes
ignore the signal block and terminate the application -- Darwin appears
to be an exception, but vfork() is not enabled there. Both situations
are tested by terminateInChildProcessModifier().
Task-number: QTBUG-113822
Change-Id: Ib5ce7a497e034ebabb2cfffd17628ca33969b7af
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
bd32c7d705