Reduce string allocations.
Reduce string allocations.

Before total allocations = 69010
```
[[rack/lib/rack/utils.rb", 314, :T_STRING], [39000, 22, 38009, 0, 27, 2536600]]
[[rack/lib/rack/utils.rb", 312, :T_STRING], [12004, 0, 11518, 0, 2, 464800]]
[[rack/lib/rack/utils.rb", 313, :T_STRING], [18006, 0, 17274, 0, 1, 2803325]]
```

After total allocations = 45000
```
[[rack/lib/rack/utils.rb", 315, :T_STRING], [45000, 41, 45338, 0, 28, 4160731]]
```

keithduncan/rack,nmk/rack,jackxxu/rack,davydovanton/rack,shaneog/rack,stepri/rack,davydovanton/rack,Codeman655/rack,Eric-Guo/rack,keithduncan/rack,supzann3/rack,wildjcrt/rack,maclover7/rack,gioele/rack,wjordan/rack,liamseanbrady/rack,laplaceliu/rack,tylergannon/rack,jackxxu/rack,ngpestelos/rack,liamseanbrady/rack,jeremyf/rack,imtayadeway/rack,davidcelis/rack,zjsxwc/rack,Eric-Guo/rack,imtayadeway/rack,Codeman655/rack,davidcelis/rack,jeremyf/rack,gioele/rack,keithduncan/rack,gfvcastro/rack,Comcast/rack,shaneog/rack,keepcosmos/rack,ganmacs/rack,trexnix/rack,rwz/rack,keepcosmos/rack,arronmabrey/rack,liamseanbrady/rack,tylergannon/rack,nmk/rack,AMekss/rack,davydovanton/rack,eavgerinos/rack,stepri/rack,Comcast/rack,laplaceliu/rack,gfvcastro/rack,ngpestelos/rack,rwz/rack,supzann3/rack,stepri/rack,supzann3/rack,tylergannon/rack,fabianrbz/rack,deepj/rack,gfvcastro/rack,eins78/rack,akihiro17/rack,wjordan/rack,ganmacs/rack,arronmabrey/rack,trexnix/rack,jackxxu/rack,Comcast/rack,maclover7/rack,ganmacs/rack,eins78/rack,eavgerinos/rack,eavgerinos/rack,deepj/rack,AMekss/rack,wildjcrt/rack,Eric-Guo/rack,davidcelis/rack,Codeman655/rack,fabianrbz/rack,arronmabrey/rack,trexnix/rack,jeremyf/rack,nmk/rack,keepcosmos/rack,rwz/rack,wildjcrt/rack,shaneog/rack,maclover7/rack,akihiro17/rack,ngpestelos/rack,deepj/rack,zjsxwc/rack,AMekss/rack,eins78/rack,fabianrbz/rack,akihiro17/rack,imtayadeway/rack,wjordan/rack,gioele/rack,zjsxwc/rack,laplaceliu/rack