Genie:  Just call fsync() from fdatasync()
vfs:  Add fsync method slot
Genie:  Provide fsync method for Mac filehandles
vfs:  Add fsync() primitive
Genie -> relix:  Move/revise fsync() system call

Call the vfs::fsync() primitive instead of StreamHandle's Synchronize().

This orphans Rsrc_IOHandle::Synchronize() (i.e. it won't ever get called
until this is fixed).
Genie:  Axe StreamHandle::Synchronize()
Merge branch 'fsync'