Motor City Online apparently checks for a debugger by setting this flag and then
intentionally causing a page fault. If no debugger is present on Windows, the
subprocess simply dies without spawning any crash dialog. This patch emulates
that behaviour, suppressing a (harmless) crash dialog from winedbg.

This may result in legitimate failures no longer triggering a winedbg crash
dialog, if other programs happen to use SEM_NOGPFAULTERRORBOX, but the winedbg
crash dialog cannot be relied upon anyway.