Synchronizes the contents of memory to file.
If memory.len is greater than file size, the bytes beyond the end of the
file may be dropped, or they may be written, extending the size of the
file.
pub fn write(mm: *MemoryMap, io: Io) File.WritePositionalError!void
pub fn write(mm: *MemoryMap, io: Io) File.WritePositionalError!void {
return io.vtable.fileMemoryMapWrite(io.userdata, mm);
}