Bug 40708: tor.exe in tor-expert-bundle not writing stdout even when run from cmd.exe

Added explicit -Wl,--subsystem,console targets/windows/var/flag_mwindows so that tor.exe will spawn a terminal window. Firefox still keeps it hidden because of the changes to tor-launcher.

We didn't need this when we were using gcc because -mconsole was the default, but now that we've switched to clang we have to explicitly tell the linker to use the right windows stuffs to spawn a terminal window, othewise the daemon just runs in the background.

Fixes #40708 (closed)