Avoid calling libtool to link every single test case, by building just one
binary from all the sources.
This binary is then given the task of choosing tests to run (based on user
selection and individual test requirement), forking each test into its own
process and accumulating the results.
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 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 test case back when
some other means of requesting that font face is added.
