But disable the gcrypt plugin, as it causes leaks.
Also disable the backtraces by libunwind as they seem to cause
threads to get cleaned up after the leak detective already has been
disabled, which leads to invalid free()s.
Not sure if 4 jobs is optimal, but according to the docs each build host
has 1.5 virtual cores available (although "getconf _NPROCESSORS_ONLN"
returns 32, which is probably the number of real cores underneath), so
more jobs might not actually reduce the build time much more.
Martin Willi