Calvin Xiao 53ececda21
caddyhttp: performance improvement in HeaderRE Matcher (#4143)
Below is the report using `benchstat` and cmd:

`go test -run=BenchmarkHeaderREMatcher -bench=BenchmarkHeaderREMatcher -benchmem -count=10`

```
name                old time/op    new time/op    delta
HeaderREMatcher-16     869ns ± 1%     658ns ± 0%  -24.29%  (p=0.000 n=10+10)

name                old alloc/op   new alloc/op   delta
HeaderREMatcher-16      144B ± 0%      112B ± 0%  -22.22%  (p=0.000 n=10+10)

name                old allocs/op  new allocs/op  delta
HeaderREMatcher-16      7.00 ± 0%      5.00 ± 0%  -28.57%  (p=0.000 n=10+10)
```
2021-05-02 10:35:28 -06:00
..