Problem: INI files not detected
Solution: detect uppercase .INI as dosini files
It previo~1 only worked for lower-case .ini files, but upperc~1 .INI is
also somewhat common on account of DOS' old 8.3 upperc~2 only filena~1.
closes: vim/vim#133164a82bdfaa8
Co-authored-by: Martin Tournoij <martin@arp242.net>