Use GCC and remove sandboxing mechanisms. (#4658)
* Use GCC and remove sandboxing mechanisms.
* Split `libxla_computation_client.so` into libraries. (#4659)
* Split `libxla_computation_client.so` into libraries.
To do this split, reworked the metrics analysis.
Currently, metrics analysis would get a global singleton
of the computation client to get the metrics. This change
switches to injection, so the python bindings init can use
the singleton to pass the metrics down to the analysis,
removing the dependency from the analysis to the whole client.
Add some tests.
* Remove running tests; they are not cached and are slow. They are not run anyway as is.
