shadow: use proper fix for checking subordinate IDs support

shadow: use proper fix for checking subordinate IDs support

During 4.2.1 version update support for subordinate IDs has been
disabled. It was handled by:

1) Adding --disable-subordinate-ids to avoid:
configure: error: cannot run test program while cross compiling

2) Adding patch 003-fix-disabling-subids.patch to avoid:
usermod.c: In function 'process_flags':
usermod.c:1364:10: error: 'vflg' undeclared (first use in this function)
  if (   (vflg || Vflg)
          ^

This commit adds a patch with a proper configure.in fix. We don't need
to disable subordinate IDs anymore.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>