patch 7.4.1975

Problem:    On MS-Windows large files (> 2Gbyte) cause problems.
Solution:   Use "off_T" instead of "off_t".  Use "stat_T" instead of "struct
            stat".  Use 64 bit system functions if available.  (Ken Takata)

src/spell.c

@@ -9037,7 +9037,7 @@ mkspell(
     afffile_T	*(afile[8]);
     int		i;
     int		len;
-    struct stat	st;
+    stat_T	st;
     int		error = FALSE;
     spellinfo_T spin;