Alexander Larsson authored Dec 18, 2009 and Colin Walters committed May 27, 2010

This adds static markers for dtrace, which are also usable
by systemtap. Additionally it adds a tapset for systemtap
that makes it easier to use the static markers.

These are enabled by default.

This initial set of probes is rather limited:

* allocation and free using g_malloc & co
* allocation and free using g_slice
* gquark name tracking (useful for converting quarks to strings in probes)

Notes on naming:

Its traditional with dtrace to use probe names with dashes as
delimiter (slice-alloc). Since dashes are not usable in identifiers
the C code uses double underscores (slice__alloc) which is converted
to dashes in the UI. We follow this for the shared lowlevel probe
names.

Additionally dtrace supports putting a "provider" part in the probe
names which is essentially a namespacing thing. On systemtap this
field is currently ignored (but may be implemented in the future), but
this is not really a problem since in systemtap the probes are
specified by combining...