Darwin added support in its Xcode 8.0 tools (released in the beta) for universal
files where offsets and sizes for the objects are 64-bits to allow support for
objects contained in universal files to be larger then 4gb. The change is very
straight forward. There is a new magic number that differs by one bit, much
like the 64-bit Mach-O files. Then there is a new structure that follow the
fat_header that has the same layout but with the offset and size fields using
64-bit values instead of 32-bit values.
rdar://26899493
llvm-svn: 273207