proc_addr() returns address based on location in proc array

- pproc_addr is not neccessary to get the address of a process if we know its
  number

- local proc variables in system calls implementation (sys_task) conflicts with
  the global proc array of all process, therefore the variable were renamed to
  proc_nr as they hold the process number

kernel/proc.h

@@ -198,7 +198,7 @@ struct proc {
 #define NIL_PROC          ((struct proc *) 0)		
 #define NIL_SYS_PROC      ((struct proc *) 1)		
 #define cproc_addr(n)     (&(proc + NR_TASKS)[(n)])
-#define proc_addr(n)      (pproc_addr + NR_TASKS)[(n)]
+#define proc_addr(n)      (&(proc[NR_TASKS + (n)]))
 #define proc_nr(p) 	  ((p)->p_nr)
 
 #define isokprocn(n)      ((unsigned) ((n) + NR_TASKS) < NR_PROCS + NR_TASKS)