Patches for magicmny

I had to make a few patches for pgptools and magic money to compile on
a dos system with microsoft c 6.0.

#include <mem.h>
and
#include <io.h>

do not work with this compiler.  I added #ifdef __TURBOC__ around
these includes in mm.c, s.c, c.c, and ptd.c.

In pgpmem.c, this system has malloc.h but not alloc.h.  Change the #ifdef MSDOS
to #ifdef __TURBOC__.

With these changes it worked.