Add wrappers for accessing PID and command info

This change adds simple wrappers for accessing a thread's PID and
command character string.

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #296

include/sys/thread.h

@@ -51,6 +51,8 @@ typedef void (*thread_func_t)(void *);
 #define thread_exit()			__thread_exit()
 #define thread_join(t)			VERIFY(0)
 #define curthread			current
+#define getcomm()			current->comm
+#define getpid()			current->pid
 
 extern kthread_t *__thread_create(caddr_t stk, size_t  stksize,
                                   thread_func_t func, const char *name,