[RFC] ARM support for syscall tracing

[Steven Walter]

I recently noticed that "perf test" fails tests #2 - #4 on ARM.  In
investigating that failure, I noticed that those tests rely on
FTRACE_SYSCALLS, which was not available on ARM.

It didn't look like too much work to enable HAVE_SYSCALL_TRACEPOINTS, so
that's what I did in the patches that follow.  This is a
request-for-comment because I don't entirely understand some of the
changes I made, so it's quite likely that some parts are either
out-and-out wrong, or at least can be done a better way.

That said, the tests in "perf test" pass except for #1 (kallsyms), and
strace still seems to report sensible values for system calls.

Comments?