Widen the scope of filetype matches

The original pattern was fairly limited - widen it to support a
SYSCONFDIR under /usr/local/etc. Also modify the pattern to look in
subdirs of /etc/lighttpd/ and /usr/local/etc/lighttpd/

Cherry-Picked:
	https://github.com/jaset/vim-syntax-lighttpd/commit/51545ca310877da78d6db148bbee94151095c0a2
Conflicts:
	ftdetect/lighttpd.vim