Our overall nightly test time greatly decreases when the timeouts for
the single tests are not that over-pessimistic. Using the slowest
platforms as reference, this commit reduces the test timeouts.
Ref #3027
The pthread API is considered a standard feature of libc so better to
simply merge it with the libc. Pthreads are in fact already a part of
the libc in the form of weak symbols. This merger is also a prerequisite
for better integrating pthreads with the libc I/O task.
Fix#3054
