Fix text replacement warning

Using strncpy to cut off copying a terminating NUL yields a gcc
warning.  Just use memcpy instead.

src/write.c

@@ -171,7 +171,7 @@ register struct obj *pen;
         nm += 3;
 
     if ((bp = strstri(nm, " armour")) != 0) {
-        (void) strncpy(bp, " armor ", 7); /* won't add '\0' */
+        memcpy(bp, " armor ", 7);
         (void) mungspaces(bp + 1);        /* remove the extra space */
     }