used to get and set the thread user value, which is an opaque pointer to
a per thread structure stored in userland. cthread_self() is used by Darwin
as an implementation for pthread_self(), which return the thread id.
We use the p_emuldata field of struct proc in order to keep track of the
thread user value. For now the value is per-process, but we will make it
per-thread when we will take care of threading.
While we are there, do some KNF
macho_hdr, argc, *argv, NULL, *envp, NULL, progname, NULL,
*progname, **argv, **envp
Where progname is a pointer to the program name as given in the first
argument to execve(), and macho_hdr a pointer to the Mach-O header at
the beginning of the executable file.
manu