new version by mjw in attachment 390110 of rhbz:545179, as this should
eliminate the performance penalty for the case where the probes aren't
in use, and eliminate all architecture-specific code (rhbz:563541;
except on sparc)
- update some comments in specfile relating to gdb work
- manually byte-compile the gdb.py file with the freshly-built python to
ensure that .pyx and .pyo files make it into the debuginfo manifest if
they are later byte-compiled after find-debuginfo.sh is run