I forgot to fix this one before pushing, despite my tests. lockon_ptr is
only used to compare pointers, it doesn't need to point to a writable
location. Without threads the atomic store is turned into an assignment
and rightfully complains.
Given that we can pass typed arguments to the trace() function, let's
add provisions for tracking them. They are source-specific so we need
to let the source fill their name and description. Only those with a
non-null name will be proposed.
With a few macros it's possible for a trace source to commit to only
using a certain type for a given argument (or set of). This will be
particularly useful to let the trace subsystem retrieve some precious
information such as a connection, session, listener, source address or
so, and enable/disable filtering and/or locking.
The principle of this subsystem will be to support taking live traces
at various places in the code with conditional triggers, filters, and
ability to lock on some elements. The traces will support typed events
and will be sent into sinks made of ring buffers, file descriptors or
remote servers.
