Fixed compiler warnings related to const, unreachable code, and an empty translation unit.

src/winmain.c

@@ -1641,4 +1641,14 @@ winmessage(char *new_msg)
 }
 
 
+
+#else /* HAS_WINGUI not defined */
+/* Prevent warning regarding empty translation unit */
+static void dummy(void)
+{
+    return;
+} /* end of function dummy */
+
+
+
 #endif /* HAS_WINGUI */

src/xspice/mif/mifutil.c

@@ -142,7 +142,6 @@ char  *MIFgettok(char **s)
         }
         break;
     }
-    return NULL; /* should not happen */
 }
 
 #if 0