ARROW-1591: C++: Xcode 9 is not correctly detected
ARROW-1591: C++: Xcode 9 is not correctly detected

Author: Uwe L. Korn <uwelk@xhochy.com>

Closes #1121 from xhochy/ARROW-1591 and squashes the following commits:

0b3a11a [Uwe L. Korn] ARROW-1591: C++: Xcode 9 is not correctly detected

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