ARROW-2346: [Python] Fix PYARROW_CXX_FLAGS with multiple options
ARROW-2346: [Python] Fix PYARROW_CXX_FLAGS with multiple options

Quoting seems necessary only when going through the shell.

Author: Antoine Pitrou <antoine@python.org>

Closes #1783 from pitrou/ARROW-2346-multiple-pyarrow-cxxflags and squashes the following commits:

6599ab0 <Antoine Pitrou> ARROW-2346:  Fix PYARROW_CXX_FLAGS with multiple options

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