add port information
Fix compilation failures under Intel C compiler.

It appears that Intel C compiler doesn't recognize unsigned wchar_t,
however it doesn't appear to be important (the conversion function is
unused, and in other cases it doesn't appear to be needed).
Disallow Unicode conversion specifications.

This stops fish from accessing the `bool ok[UCHAR_MAX + 1]` table
beyond allocated space potentially accessing memory that doesn't
belong to fish, and crashing.
Implemented iothread_perform_on_main() to support background threads
scheduling work on main thread
Merge remote-tracking branch 'upstream/master'