The cr16 libgloss port does not define these syscall numbers, so trying
to use them results in build failures [1]. The cr16 code already uses
ifdefs around a bunch of syscalls, so extend that style to cover the
ones that are currently missing. Now we can at least compile.
[1] http://sourceware.org/ml/gdb-patches/2011-06/msg00118.html
Signed-off-by: Mike Frysinger <vapier@gentoo.org>