a possible micro-optimization

[Poul-Henning Kamp]

This is a crudely hacked together proof-of-concept where a "perfect hash"
is used to find out if a given HTTP header has filtering flags.

I expect, but am far from sure, that this will perform better than the
current sequential code.

If anybody has a chance to beat this up in some kind of a performance
test, I would be very interested to hear the results.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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