Allow MICRO and WIN32 code paths to diverge

There's still a lot of overlap for 3.4.1, but not
100% any longer and it facilitates some improvements
- Allow error save files on WIN32

win/share/tile.h

@@ -38,7 +38,7 @@ extern int NDECL(fclose_text_file);
 extern void NDECL(init_colormap);
 extern void NDECL(merge_colormap);
 
-#if defined(MICRO)
+#if defined(MICRO) || defined(WIN32)
 #undef exit
 # if !defined(MSDOS) && !defined(WIN32)
 extern void FDECL(exit, (int));

win/share/tilemap.c

@@ -13,7 +13,7 @@ const char * FDECL(tilename, (int, int));
 void NDECL(init_tilemap);
 void FDECL(process_substitutions, (FILE *));
 
-#ifdef MICRO
+#if defined(MICRO) || defined(WIN32)
 #undef exit
 #if !defined(MSDOS) && !defined(WIN32)
 extern void FDECL(exit, (int));