Modify structures in libfuse to handle flags beyond 32 bits.

Modify structures in libfuse to handle flags beyond 32 bits.

In fuse kernel, 'commit 53db28933e95 ("fuse: extend init flags")'
made the changes to handle flags going beyond 32 bits but i think
changes were not done in libfuse to handle the same.

This patch prepares the ground in libfuse for incoming FUSE kernel
patches (Atomic open + lookup) where flags went beyond 32 bits.
It makes struct same as in fuse kernel resulting in name change of
few fields.