ARROW-1169: [C++] jemalloc externalproject doesn't build with CMake's ninja generator
ARROW-1169: [C++] jemalloc externalproject doesn't build with CMake's ninja generator

Closes #796

Change-Id: I3cbd06d774feca254183e0ed1b0e75111f7cb389

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