Blender Git Loki

Cleanup: 64 bit file IO on windows.

Unlike Linux where fseek/tell will be either 32 or 64 bit
depending on the target platform, it will always be 32 bit
on windows.

We had some macro magic in BLI_winstuff.h that substituted
them for 64 bit versions, but that is upsetting the system
headers if they get included after BLI_winstuff.h which
is problematic for D6811.

This diff adds proper functions in blenlib and updates
all calls that were using the BLI_winstuff.h header to
gain 64 bit file IO.

note: Anything that was using the 32 bit versions (ie not
including BLI_winstuff.h) will still be using the 32 bit
versions, which is perhaps a good code quality Friday project.

Differential Revision: https://developer.blender.org/D7160

Reviewers: brecht dfelinto