More cleanup to remove MM and FS references

lib/libsys/sys_kill.c

@@ -4,7 +4,7 @@ PUBLIC int sys_kill(proc_ep, signr)
 endpoint_t proc_ep;		/* which proc_ep has exited */
 int signr;			/* signal number: 1 - 16 */
 {
-/* A proc_ep has to be signaled via MM.  Tell the kernel. */
+/* A proc_ep has to be signaled via PM.  Tell the kernel. */
   message m;
 
   m.SIG_ENDPT = proc_ep;

lib/libsys/taskcall.c

@@ -1,6 +1,6 @@
 /* _taskcall() is the same as _syscall() except it returns negative error
- * codes directly and not in errno.  This is a better interface for MM and
- * FS.
+ * codes directly and not in errno.  This is a better interface for PM and
+ * VFS.
  */
 
 #include <lib.h>