In order to handle 'cairo-perf-trace benchmark', we need to perform the
can_run? test on the directory name as opposed to the individual trace
names. Make it so.
By ensuring that tests take longer than a couple of seconds we eliminate
systematic errors in our measurements. However, we also effectively
eliminate the synchronisation overhead. To compensate, we attempt to
estimate the overhead by reporting the difference between a single
instance and the minimum averaged instance.
Behdad wants to include the feature with 1.10, so we enable it as early as
possible in 1.9 dev cycle to generate as much feedback as possible.
The first change is to use "<cairo>" as being a name unlikely to clash
with any real font names.
This reverts commits:
a824d284be,
2922336855,
e0046aaf41,
f534bd549e.
This performance test relied on the recently-removed ability
to select the internal twin-based font family with a name of
"cairo".
Presumably, we'll want to bring this performance case back when
some other means of requesting that font face is added.
