Fix `xmalloc_readlink()` again

In e86a3ddd8 (win32: make readlink(2) implementation unconditional,
2021-02-12), we removed the special casing of `errno == ENOSYS` when
trying to follow symlinks. However, that handling really was necessary:

- When we followed a symlink, and found a non-symlink, and then called
  `readlink()` with that non-symlink, we got `errno == ENOSYS` on
  Windows (translated from `ERROR_NOT_A_REPARSE_POINT`), and we did
  want to stop the loop and return the current path in that case.
  (Noted by Johannes Schindelin.)

- When readlink() called DeviceIoControl() for files on certain
  filesystems (e.g. FAT or a CDROM) it returned `errno == ENOSYS`
  (translated from ERROR_INVALID_FUNCTION).

Revert the part of the patch which handled `ENOSYS` on Windows.

1 files changed, 1 insertions, 1 deletions

diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
index a18dd0748..ca53e12d3 100644
--- a/libbb/xreadlink.c
+++ b/libbb/xreadlink.c
@@ -64,7 +64,7 @@ char* FAST_FUNC xmalloc_follow_symlinks(const char *path)
                 linkpath = xmalloc_readlink(buf);
                 if (!linkpath) {
                         /* not a symlink, or doesn't exist */
-                        if (errno == EINVAL || errno == ENOENT)
+                        if (errno == EINVAL || errno == ENOENT || (ENABLE_PLATFORM_MINGW32 && errno == ENOSYS))
                                 return buf;
                         goto free_buf_ret_null;
                 }