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/os_win32.c

@@ -3058,7 +3058,7 @@ mch_dirname(
     long
 mch_getperm(char_u *name)
 {
-    struct stat st;
+    stat_T	st;
     int		n;
 
     n = mch_stat((char *)name, &st);