make it compile under MSN vc. Unfortunately it has a weird crash at boot :(

- Lots of indenting changes
- VC++ is strict with variadic macros
- VC++ does not accept unistd.h
- new interface for walltime
- VC++ does not seem to have support for integer overflow.
- VC++ defines YENV_REG?
- no access flags, x permissions ignored.
- new FindGMP supporting MPIR
- make horus optional (c++ is hard).

os/alias.c

@@ -68,7 +68,6 @@ static char SccsId[] = "%W% %G%";
 #include <stdarg.h>
 #endif
 #ifdef HAVE_UNISTD_H
-
 #include <unistd.h>
 #endif
 #if HAVE_CTYPE_H