Add /* unprivileged */ to a variety of tapset embedded-c functions,
together with uid-assertion-checking code as needed.  This is only
an initial set, and may need to grow or shrink after further testing.

Prototyped-By: Dave Brolley <brolley@redhat.com>

* runtime/runtime.h (is_myproc, assert_is_myproc): New macros.
* runtime/addr-map.c (lookup_bad_addr): Reject if !is_myproc
  in unprivileged mode.
* runtime/print.c (_stp_print_kernel_info): Add unprivileged
  mode info.
* tapset/DEVGUIDE: Document /* pure */ and /* unprivileged */.
* tapset/*.stp: Add /* unprivileged */ here and there, in
  questionable cases along with an assert_is_myproc().

The overlapping process.* tapsets are now separated.  Those probe points
documented in stapprobes(3stap) remain the same.  Those that were formerly
in stapprobes.process(3stap) have been renamed to kprocess, to reflect
their kernel perspective on processes.

Getting rid of ChangeLogs doesn't mean that we get a free ticket -- we
now need to be more diligent about providing meaningful commit messages.
I've updated the HACKING file with a first draft of new guidelines, but
we may still revise what we feel is appropriate detail in the logs.

I removed the ChangeLog section from the tapset/DEVGIDE entirely, and
also fixed the path where examples are stored.