Advanced Rogue family: overhaul privilege handling.

Advanced Rogue 5 and 7, and XRogue, now open the scorefile and logfile
at startup and then drop any set[ug]id privileges if the savedir is not
being used.

arogue7/mach_dep.h

@@ -44,6 +44,15 @@
 #define SCOREFILE	"arogue7.scr"
 #endif
 
+#ifndef LOGFILE
+#define LOGFILE "arogue7.log"
+#endif
+
+#ifndef SAVEDIR
+#define SAVEDIR "."
+#endif
+
+
 /*
  * Variables for checking to make sure the system isn't too loaded
  * for people to play