Genie:  Move LookUpSystemCallByName() to call site
Genie -> relix:  Move system call dispatchers
Genie:  Axe Genie/api/breathe.hh
Genie:  Use only relix in current_stack_base()
Genie -> relix:  Move current_stack_base()
relix:  Don't dup current_stack_base() declaration
Genie:  Move New_FSTree_sys_mac_tempmem() into vfs

Rename New_FSTree_sys_mac_tempmem() to new_sys_mac_tempmem() and move it
into namespace vfs.  Remove the dependency on Genie as well.
Genie -> MacVFS:  Move /sys/mac/tempmem logic
vfs:  Fix read/write to non-regular files

Call POSIX read() and write() (via poseven).  Otherwise, vfs provides an
implementation that calls pread() or pwrite(), which fails with EPIPE on
FIFOs and other non-regular files.