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).

C/flags.c

@@ -1018,13 +1018,13 @@ Term Yap_UnknownFlag(Term mod) {
        mod = TermProlog;
 
       ModEntry *fv = Yap_GetModuleEntry(mod);
-      if (fv == NULL)
-        fv = Yap_GetModuleEntry(TermUser);
-      if (fv->flags & UNKNOWN_ERROR)
-        return TermError;
-      if (fv->flags & UNKNOWN_WARNING)
-        return TermWarning;
-      return TermFail;
+  if (fv == NULL)
+     fv = Yap_GetModuleEntry(AtomUser);
+     if (fv->flags & UNKNOWN_ERROR)
+      return TermError;
+    if (fv->flags & UNKNOWN_WARNING)
+      return TermWarning;
+    return TermFail;
 }
 
 Term getYapFlag(Term tflag) {