[PATCH] match: use re2 in readpatternfile if possible

[Sean Farley]

Bryan O'Sullivan <bos at serpentine.com> writes:

> # HG changeset patch
> # User Bryan O'Sullivan <bos at serpentine.com>
> # Date 1449194374 28800
> #      Thu Dec 03 17:59:34 2015 -0800
> # Node ID e41d4b2eb41eaba7ff2c1e7f4f110253574455e3
> # Parent  df9b73d2d444ae82fe8d3fe6cf682a93b2c4a7ef
> match: use re2 in readpatternfile if possible
>
> This has a small, but measurable, effect on performance if a pattern
> file is very large.  In an artificial test with 200,000 lines of
> pattern data, using re2 reduced read time by 200 milliseconds.

Now you're just showing off ;-P