These don't take a duration, instead they call g_get_monotonic_time() to
and subtract the start time for it.
Almost all our calls are like this, and this makes the callsites clearer
and avoids inlining the clock call into the call site.
When we use if (GDK_PROFILER_IS_RUNNING) this means we get an
inlined if (FALSE) when the compiler support is not compiled in, which
gets rid of all the related code completely.
We also expand to G_UNLIKELY(gdk_profiler_is_running ()) in the supported
case which might cause somewhat better code generation.
This allows us to avoid hand-rolling g_strdup_printf calls,
but also moves the printf into the called function where
it doesn't bloat the code of the calling function if the profiler
is not running.
This is writing data in the capture format of sysprof,
using the SpCaptureWriter. For now, this is using a
vendored copy of libsysprof. Eventually, we want to
use the static library that sysprof provides.
