resolv.conf option parsing: Fix word separation
`nextword' does not nul-terminate the words it returns. So the
strcmps in ccf_options are wrong. Fix this as follows:
* Abolish most uses of l in favour of a pointer variable endword.
* Have OPTION_IS and OPTION_STARTS update word, and endword, so
that it is convenient to use them for option values, etc.
* Save the whole option in new variables opt and optend for
reporting and to assist the `adns_af:' loop.
* Use OPTION_IS, OPTION_STARTS and memchr, rather than strcmp,
ad-hoc memcmp, and strcspn.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
~mdw / adns / commit