* tapset/conversions.stp (kernel_pointer): Use uintptr_t casts.
* tapset/conversions-guru.stp (set_kernel_pointer): Ditto.

* translate.cxx (MAX_UNWIND_TABLE_SIZE): Double to 6MB.
  (dump_unwindsyms): Handle excess .eh_frame, .eh_frame_hdr,
  .debug_frame sizes as suppressible warnings instead of
  semantic_errors.

* runtime/task_finder.c (__stp_call_mmap_callbacks_with_addr): Avoided
  uninitialized variable error.

The former code allowed stapio to have two concurrent commands sent
toward the runtime at the same time: one from the main loop and
another one from the signal handling thread.  This is suspected to
have caused occasional lockups.  This new code switches to a deferred
signal handling model, where the signal handling thread merely
increments a counter, and the main loop monitors that count.
Unfortunately, this currently involves switching the main loop's
blocking /.ctl read into a nonblocking poll.

* runtime/staprun/mainloop.c (pending_interrupts): New variable.
  (signal_thread): Increment it.
  (stp_main_loop): Check it.

* dwflpp.cxx (build_blacklist): Add a few more entries.

* main.cxx: Add "--compatible=VERSION" option.
* session.h (compatible): Store it.
* parse.cxx (eval_pp_conditional): Look at it as %( systemtap_v CMP VALUE ... %)
* stap.1.in: Document it.
* testsuite/parseko/preprocess17.stp, parseok/twenty.stp: Test it.

* runtime/sym.c: Store individual rc's for build-id comparisons.