The /usr/include/python/pyconfig.h file pollutes the global
namespace with a huge number of HAVE_XXX and WITH_XXX
defines. These change what we detected in our own config.h
In particular if you try to build without DTrace, python's
headers turn it back on with predictable fail.

THe hack to workaround this is to rename WITH_DTRACE to
WITH_DTRACE_PROBES to avoid the namespace clash