[patch] account for undefined or unavailable syscalls

[Roland McGrath]

That's not the right solution.  The syscall number assignments are fixed,
even if you are using a system where they don't come up.  More likely in
practice is to use an ancient <asm/unistd.h> to compile strace even though
the binary may be run on much newer kernels.  

If necessary __NR_* macros are missing, you should add them in defs.h as
has been done for other machines.


Thanks,
Roland