These were declared in pref.h and defined in subsurfacestartup.c.
pref.c didn't even exist. Create it and move preferences-related
structs and functions there.
setup_system_prefs() is left in subsurfacestartup.c, since it
works with environment variables.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
