patch 8.2.1215: Atari MiNT support is outdated

Problem:    Atari MiNT support is outdated.
Solution:   Nobody responded this code is still useful, so let's delete it.
diff --git a/src/fileio.c b/src/fileio.c
index e462310..189d4f4 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -13,7 +13,7 @@
 
 #include "vim.h"
 
-#if defined(__TANDEM) || defined(__MINT__)
+#if defined(__TANDEM)
 # include <limits.h>		// for SSIZE_MAX
 #endif
 #if defined(UNIX) && defined(FEAT_EVAL)