Define sensible INSTALL-NONBLOCK-FLAG for (and sbcl win32).
Define sensible INSTALL-NONBLOCK-FLAG for (and sbcl win32).

Unofficial threaded win32 fork provides a FIONBIO constant. If it's
BOUNDP, let's call an appropriate ioctl on the fd. Otherwise the
original do-nothing semantics is fully preserved.

With mainline (unpatched) SBCL/win32, CL+SSL stream unwrapping is
going to fail, as FD-STREAM-FD returns a CRT descriptor while openssl
expects a kernel object handle. Even though some uses of CL+SSL remain
possible despite this problem, it still makes catering to the patched
SBCL/win32 seem more reasonable.

deadtrickster/cl-plus-ssl,bsmr-common-lisp/cl-plus-ssl,Ferada/cl-plus-ssl,Ferada/cl-plus-ssl,deadtrickster/cl-plus-ssl