ARROW-4282: [Rust] builder benchmark is broken
ARROW-4282: [Rust] builder benchmark is broken

Author: Paddy Horan <paddyhoran@hotmail.com>

Closes #3422 from paddyhoran/bench-bug and squashes the following commits:

e8e7c9da <Paddy Horan> Bug fix in builder benchmark

apache/arrow,cpcloud/arrow,itaiin/arrow,wesm/arrow,laurentgo/arrow,itaiin/arrow,apache/arrow,itaiin/arrow,itaiin/arrow,tebeka/arrow,icexelloss/arrow,apache/arrow,xhochy/arrow,xhochy/arrow,itaiin/arrow,cpcloud/arrow,majetideepak/arrow,xhochy/arrow,cpcloud/arrow,laurentgo/arrow,kou/arrow,majetideepak/arrow,icexelloss/arrow,pcmoritz/arrow,renesugar/arrow,icexelloss/arrow,tebeka/arrow,cpcloud/arrow,apache/arrow,majetideepak/arrow,kou/arrow,kou/arrow,itaiin/arrow,laurentgo/arrow,kou/arrow,xhochy/arrow,majetideepak/arrow,pcmoritz/arrow,icexelloss/arrow,pcmoritz/arrow,renesugar/arrow,kou/arrow,apache/arrow,kou/arrow,laurentgo/arrow,renesugar/arrow,tebeka/arrow,majetideepak/arrow,pcmoritz/arrow,pcmoritz/arrow,wesm/arrow,icexelloss/arrow,wesm/arrow,wesm/arrow,itaiin/arrow,pcmoritz/arrow,laurentgo/arrow,tebeka/arrow,laurentgo/arrow,cpcloud/arrow,apache/arrow,itaiin/arrow,wesm/arrow,xhochy/arrow,xhochy/arrow,kou/arrow,renesugar/arrow,renesugar/arrow,icexelloss/arrow,itaiin/arrow,laurentgo/arrow,laurentgo/arrow,wesm/arrow,kou/arrow,renesugar/arrow,apache/arrow,renesugar/arrow,kou/arrow,laurentgo/arrow,icexelloss/arrow,icexelloss/arrow,tebeka/arrow,icexelloss/arrow,xhochy/arrow,wesm/arrow,cpcloud/arrow,renesugar/arrow,majetideepak/arrow,itaiin/arrow,majetideepak/arrow,icexelloss/arrow,wesm/arrow,xhochy/arrow,xhochy/arrow,majetideepak/arrow,wesm/arrow,pcmoritz/arrow,cpcloud/arrow,pcmoritz/arrow,renesugar/arrow,majetideepak/arrow,itaiin/arrow,apache/arrow,apache/arrow,icexelloss/arrow,cpcloud/arrow,renesugar/arrow,tebeka/arrow,wesm/arrow,majetideepak/arrow,kou/arrow,itaiin/arrow,icexelloss/arrow,laurentgo/arrow,kou/arrow,tebeka/arrow,apache/arrow,tebeka/arrow,tebeka/arrow,wesm/arrow,renesugar/arrow,itaiin/arrow,xhochy/arrow,laurentgo/arrow,cpcloud/arrow,icexelloss/arrow,pcmoritz/arrow,cpcloud/arrow,majetideepak/arrow,tebeka/arrow,pcmoritz/arrow,xhochy/arrow,laurentgo/arrow,pcmoritz/arrow,wesm/arrow,majetideepak/arrow,majetideepak/arrow,renesugar/arrow,itaiin/arrow,renesugar/arrow,cpcloud/arrow,renesugar/arrow,kou/arrow,pcmoritz/arrow,itaiin/arrow,renesugar/arrow,kou/arrow,xhochy/arrow,xhochy/arrow,icexelloss/arrow,laurentgo/arrow,cpcloud/arrow,cpcloud/arrow,laurentgo/arrow,pcmoritz/arrow,apache/arrow,apache/arrow,cpcloud/arrow,wesm/arrow,apache/arrow,majetideepak/arrow,majetideepak/arrow,xhochy/arrow,xhochy/arrow,laurentgo/arrow,apache/arrow,pcmoritz/arrow,wesm/arrow,kou/arrow,pcmoritz/arrow