Add configure --disable-sdt-probes

Add configure --disable-sdt-probes

This new option turns off SDT markers in our own binaries.  This doesn't
change the ability to probe SDT in other applications.

* configure.ac: Add --disable-sdt-probes.
* runtime/staprun/configure.ac: Ditto.
* includes/stap-probe.h: Define PROBE[N] depending on ENABLE_SDT_PROBES.
* *.cxx, runtime/staprun/*.[ch]: Use the indirect PROBE macros instead
  of STAP_PROBE, so SDT can be disabled.
* (everything else): Regenerated with autoreconf.
  (The change is bigger due to my newer autotools on F14 -- sorry...)