Workaround for 64-bit MP4 atoms.
Removed an ambiguous cast from FileNameHandle to FileName.
Revert "Removed an ambiguous cast from FileNameHandle to FileName."

This reverts commit 9af7601baee66ed8fa7cac01b5dc272dd2544ee5.
Remove CMake check for sizeof(long).
Merge remote-tracking branch 'TsudaKageyu/64bit-atom'

Conflicts:
	ConfigureChecks.cmake