Fix so fthreads/wthreads doesn't require FishIO/HercIO

The Windows threading models OPTION_FTHREADS and OPTION_WTHREADS
are completely separate from the OPTION_FISHIO and OPTION_HERCIO
I/O models. Neither should require the other. OPTION_FTHREADS may
imply OPTION_FISHIO, but it should not require it (and vice versa:
use of OPTION_FISHIO should not require OPTION_FTHREADS). You
should be able to freely mix and match the two with each other.
If that's not true it's a bug that needs fixing.
Display I/O queuing model being used: FishIO or HercIO.
Test for _MSVC_ s/b #ifdef not #if.