more cross-compile warning bits

maximize warnings for NetHack sources
minimize warnings for Lua and pdcurses which we won't be changing

src/mail.c

@@ -452,6 +452,8 @@ ckmailstatus(void)
     }
 }
 
+DISABLE_WARNING_FORMAT_NONLITERAL
+
 /*ARGSUSED*/
 void
 readmail(struct obj *otmp UNUSED)
@@ -522,6 +524,8 @@ readmail(struct obj *otmp UNUSED)
         pline("It reads:  \"%s\"", junk[rn2(SIZE(junk))]);
 }
 
+RESTORE_WARNING_FORMAT_NONLITERAL
+
 #endif /* !UNIX && !VMS */
 
 #ifdef UNIX