Other implementations of pthread_setname_np() do not take the name
length as an argument.
For pthread_getname_np(), other implementations take the buffer size
as a size_t.
This patch brings us in line with other implementations.
This patch adds pthread_create() and pthread_exit(), which currently
simply wrap our existing create_thread() and exit_thread() syscalls.
LibThread is also ported to using LibPthread.
This library is meant to provide C++-style wrappers over lower
level APIs such as syscalls and pthread_* functions, as well as
utilities for easily running pieces of logic on different
threads.
