PR10650: markup some unprivileged-safe tapset functions

PR10650: markup some unprivileged-safe tapset functions

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().