BUG: BUILD_TESTING should be not advanced.
BUG: BUILD_TESTING should be not advanced.

The BUILD_TESTING CMake flag is an important, often changed flag that should
be exposed to someone configuring a build.

Change-Id: I8df756240d4f89267153241c3d8b6b365b39cac0

Kitware/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,malaterre/ITK,spinicist/ITK,BRAINSia/ITK,spinicist/ITK,Kitware/ITK,thewtex/ITK,vfonov/ITK,PlutoniumHeart/ITK,zachary-williamson/ITK,thewtex/ITK,thewtex/ITK,hjmjohnson/ITK,malaterre/ITK,richardbeare/ITK,blowekamp/ITK,hjmjohnson/ITK,blowekamp/ITK,vfonov/ITK,malaterre/ITK,zachary-williamson/ITK,BRAINSia/ITK,jcfr/ITK,hjmjohnson/ITK,stnava/ITK,fbudin69500/ITK,jcfr/ITK,richardbeare/ITK,thewtex/ITK,blowekamp/ITK,stnava/ITK,InsightSoftwareConsortium/ITK,spinicist/ITK,Kitware/ITK,Kitware/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,blowekamp/ITK,PlutoniumHeart/ITK,fbudin69500/ITK,spinicist/ITK,stnava/ITK,stnava/ITK,LucasGandel/ITK,BRAINSia/ITK,fbudin69500/ITK,zachary-williamson/ITK,jcfr/ITK,Kitware/ITK,BRAINSia/ITK,vfonov/ITK,jcfr/ITK,stnava/ITK,richardbeare/ITK,spinicist/ITK,jcfr/ITK,thewtex/ITK,malaterre/ITK,BRAINSia/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,fbudin69500/ITK,vfonov/ITK,hjmjohnson/ITK,malaterre/ITK,vfonov/ITK,hjmjohnson/ITK,malaterre/ITK,blowekamp/ITK,thewtex/ITK,zachary-williamson/ITK,spinicist/ITK,richardbeare/ITK,PlutoniumHeart/ITK,blowekamp/ITK,stnava/ITK,Kitware/ITK,stnava/ITK,jcfr/ITK,fbudin69500/ITK,spinicist/ITK,blowekamp/ITK,Kitware/ITK,zachary-williamson/ITK,malaterre/ITK,spinicist/ITK,richardbeare/ITK,hjmjohnson/ITK,LucasGandel/ITK,BRAINSia/ITK,jcfr/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,fbudin69500/ITK,zachary-williamson/ITK,InsightSoftwareConsortium/ITK,fbudin69500/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,LucasGandel/ITK,fbudin69500/ITK,zachary-williamson/ITK,LucasGandel/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,LucasGandel/ITK,richardbeare/ITK,vfonov/ITK,vfonov/ITK,zachary-williamson/ITK,stnava/ITK,PlutoniumHeart/ITK,LucasGandel/ITK,malaterre/ITK,LucasGandel/ITK,stnava/ITK,spinicist/ITK,jcfr/ITK,hjmjohnson/ITK,zachary-williamson/ITK,BRAINSia/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,LucasGandel/ITK,blowekamp/ITK