Moves socket semaphore stuff

If we end up using the sockets, we should integrate the fd->whatever
lookup differently.
Arch specific PC/IP and FP/BP helpers

Ultimately, we'll settle on read_pc and read_fp.
Semaphore debugging

Turn it on with CONFIG_SEMAPHORE_DEBUG.  The most useful way to use it
is via kfunc print_all_sem_info.