compat/mingw: rename the symlink, not the target (git-for-windows#5437)

This fixes yet another fall-out from the `mingw_rename()` change that was introduced in v2.48.0.

Author: dscho

compat/mingw.c

@@ -2926,7 +2926,9 @@ int mingw_rename(const char *pold, const char *pnew)
 
 		old_handle = CreateFileW(wpold, DELETE,
 					 FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE,
-					 NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+					 NULL, OPEN_EXISTING,
+					 FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT,
+					 NULL);
 		if (old_handle == INVALID_HANDLE_VALUE) {
 			errno = err_win_to_posix(GetLastError());
 			return -1;