mingw: support Windows Server 2016 again

It was reported to the Git for Windows project that a simple `git init`
fails on Windows Server 2016:

  D:\Dev\test> git init
  error: could not write config file D:/Dev/test/.git/config: Function not implemented
  fatal: could not set 'core.repositoryformatversion' to '0'

According to https://endoflife.date/windows-server, Windows Server 2016
is officially supported for another one-and-a-half years as of time of
writing, so this is not good.

The culprit is the `mingw_rename()` changes that try to use POSIX
semantics when available, but fail to fall back properly on Windows
Server 2016.

This fixes git-for-windows#5695.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

compat/mingw.c

@@ -2916,7 +2916,9 @@ int mingw_rename(const char *pold, const char *pnew)
 		 * current system doesn't support FileRenameInfoEx. Keep us
 		 * from using it in future calls and retry.
 		 */
-		if (gle == ERROR_INVALID_PARAMETER || gle == ERROR_NOT_SUPPORTED) {
+		if (gle == ERROR_INVALID_PARAMETER ||
+		    gle == ERROR_NOT_SUPPORTED ||
+		    gle == ERROR_INVALID_FUNCTION) {
 			supports_file_rename_info_ex = 0;
 			goto repeat;
 		}