Lws now strips out http headers releated to h2, ws and unusual headers
based on cmake config settings for those features... it saves some heap
for the ah and reduces the table size in .rodata.
It's possible code might have some external dependency on the original
header indexes, but, eg, you don't enable h2 so those indexes are
optimized with the h2 ones taken out.
This introduces a cmake option "LWS_HTTP_HEADERS_ALL", default-OFF, that
defeats the header table optimization for compatibility with older
versions in the case the client software can't be adapted to use the
lws-exported matching header enums.
You probably don't need this.
Headers related to ws or h2 are now elided if the ws or h2 role
is not enabled for build. In addition, a new build-time option
LWS_WITH_HTTP_UNCOMMON_HEADERS on by default allows removal of
less-common http headers to shrink the parser footprint.
Minilex is adapted to produce 8 different versions of the lex
table, chosen at build-time according to which headers are
included in the build.
If you don't need the unusual headers, or aren't using h2 or ws,
this chops down the size of the ah and the rodata needed to hold
the parsing table from 87 strings / pointers to 49, and the
parsing table from 1177 to 696 bytes.
