BUG: the clang version check was overly strict on Apple platforms
BUG: the clang version check was overly strict on Apple platforms

https://stackoverflow.com/a/36000632/276168 says that Apple versioning
diverged from mainline at version 7.0.

The bug was introduced by f6dd46be8a7cd3b39dd03fbe23900d27abddf6aa.

InsightSoftwareConsortium/ITK,richardbeare/ITK,vfonov/ITK,Kitware/ITK,hjmjohnson/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,malaterre/ITK,thewtex/ITK,BRAINSia/ITK,BRAINSia/ITK,richardbeare/ITK,thewtex/ITK,thewtex/ITK,Kitware/ITK,LucasGandel/ITK,thewtex/ITK,vfonov/ITK,malaterre/ITK,hjmjohnson/ITK,BRAINSia/ITK,thewtex/ITK,hjmjohnson/ITK,Kitware/ITK,LucasGandel/ITK,LucasGandel/ITK,richardbeare/ITK,thewtex/ITK,LucasGandel/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,malaterre/ITK,vfonov/ITK,LucasGandel/ITK,BRAINSia/ITK,BRAINSia/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,hjmjohnson/ITK,malaterre/ITK,hjmjohnson/ITK,LucasGandel/ITK,richardbeare/ITK,richardbeare/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,BRAINSia/ITK,thewtex/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,hjmjohnson/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,malaterre/ITK,hjmjohnson/ITK,malaterre/ITK,vfonov/ITK,LucasGandel/ITK,BRAINSia/ITK,LucasGandel/ITK,richardbeare/ITK,vfonov/ITK,richardbeare/ITK,Kitware/ITK