Performance improvement to mod_mime.c. find_ct() in mod_mime,

Performance improvement to mod_mime.c. find_ct() in mod_mime,
spends a lot of time in apr_table_get calls.  Using the default
httpd.conf, the tables for languages and charsets are somewhat
large, so the time spent scanning them on each request is
significant. Replacing the tables with hash tables provides
a nice speedup. [Brian Pane <bpane@pacbell.net>]

Had to handmerge a lot of this patch so please review! Dean had some suggestions
for improvement which are not currently implemented.

Submitted by:	Brian Pane
Reviewed by:	Bill Stoddard

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89535 13f79535-47bb-0310-9956-ffa450edef68