Create SFFS library out of HGFS

This Shared Folders File System library (libsffs) now contains all the
file system logic originally in HGFS. The actual HGFS server code is
now a stub that passes on all the work to libsffs. The libhgfs library
is changed accordingly.

include/Makefile.minix.inc

@@ -14,7 +14,7 @@ INCS+= 	minix/acpi.h minix/audio_fw.h minix/bitmap.h \
 	minix/keymap.h minix/limits.h minix/mthread.h minix/minlib.h \
 	minix/netdriver.h minix/optset.h minix/partition.h minix/portio.h \
 	minix/priv.h minix/procfs.h minix/profile.h minix/queryparam.h \
-	minix/rs.h minix/safecopies.h minix/sched.h minix/sef.h \
+	minix/rs.h minix/safecopies.h minix/sched.h minix/sef.h minix/sffs.h \
 	minix/sound.h minix/spin.h minix/sys_config.h minix/sysinfo.h \
 	minix/syslib.h minix/sysutil.h minix/timers.h minix/type.h \
 	minix/tty.h minix/u64.h minix/usb.h minix/usb_ch9.h minix/vbox.h \