process.h is now included in the proper place for compiling with MSVC.
md_sleep() has been removed. If it were used anywhere, it could have
been fixed by replacing _sleep() with Sleep().
md_shellescape() sets SIGINT and SIGQUIT to be ignored, storing the
previous handlers, and restores them after the shell exits. But it
mixed up the two handlers.
Since the signals were usually handled by the same function, this fix
doesn't have much effect, but anything that makes signal code less
confusing is a good thing.
