MERGE: strchr-speedup2 - speed up field name canonicalization

[Stefan Westerfeld <stefan space twc de>]

   Hi!

I've reimplemented the dupcanon() function in sfiprimitives.c to avoid malloc()
if possible (on already canonified input). So this is a new merge request which
should further improve the performance of my previous merge request. I tested
the function outside beast with 4 test strings, two of them already canonified,
two of them not. Performance (less is better):

766.22 - the code currently in beast/master
235.95 - my previous attempt in strchr-speedup branch
146.26 - my new code, avoiding malloc(), in strchr-speedup2 branch

Of course, the speedup within beast is less easy to predict (depends on the
strings and on whether malloc() is needed anyway, after canonicalization), but
I assume that merging the new version will speed up things a bit further than
merging the previous attempt.

repo:   http://space.twc.de/public/git/stwbeast.git
branch: strchr-speedup2

   Cu... Stefan
-- 
Stefan Westerfeld, Hamburg/Germany, http://space.twc.de/~stefan