some Microsoft compiler warnings

src/muse.c(2255) : warning C4702: unreachable code
src/options.c(2549) : warning C4702: unreachable code
src/restore.c(930) : warning C4701: potentially uninitialized local variable 'stway' used
src/sp_lev.c(5118) : warning C4701: potentially uninitialized local variable 'x' used
src/sp_lev.c(5118) : warning C4701: potentially uninitialized local variable 'y' used
src/trap.c(2979) : warning C4701: potentially uninitialized local variable 'cc' used
src/trap.c(2985) : warning C4701: potentially uninitialized local variable 'bcc' used

src/muse.c

@@ -2252,6 +2252,7 @@ struct monst *mtmp;
             }
             return 1;
         }
+        /*NOTREACHED*/
         return 0;
     case 0:
         return 0; /* i.e. an exploded wand */

src/options.c

@@ -2544,7 +2544,6 @@ char *op;
                 flags.paranoia_bits &= ~PARANOID_PRAY;
             else
                 flags.paranoia_bits |= PARANOID_PRAY;
-            return optn_ok;
         }
         return optn_ok;
     }

src/restore.c

@@ -910,7 +910,7 @@ rest_stairs(nhfp)
 NHFILE *nhfp;
 {
     int buflen = 0;
-    stairway stway;
+    stairway stway = UNDEFINED_VALUES;
     int len = 0;
 
     stairway_free_all();

src/sp_lev.c

@@ -5069,7 +5069,7 @@ lspo_terrain(L)
 lua_State *L;
 {
     terrain tmpterrain;
-    xchar x, y;
+    xchar x = 0, y = 0;
     struct selectionvar *sel = NULL;
     int argc = lua_gettop(L);
 

src/trap.c

@@ -2931,8 +2931,8 @@ long ocount;
     register int tmp;
     schar dx, dy;
     int distance;
-    coord cc;
-    coord bcc;
+    coord cc = UNDEFINED_VALUES,
+          bcc = UNDEFINED_VALUES;
     int trycount = 0;
     boolean success = FALSE;
     int mindist = 4;