Host FS MACPTR behavior for fast VLOAD

[ZeroByteOrg]

Pending Kernal PR#337 modifies the behavior of MACPTR by adding an argument to the API: C set = use "stream mode" (do not advance the dst pointer during copy from buffer) C clear = normal mode

The HostFS implementation needs to match this or else programs break, since the Kernal LOAD routine uses this argument.

[mist64]

I'll merge this at the same time as the ROM change.