top: account for the idle state ('I') threads in total

With the documentation update in the commit referenced
below, we should also account for such threads as they
will already be represented in the task/thread totals.

[ and do it in a way that might avoid future changes ]

Reference(s):
commit a238a687

Signed-off-by: Jim Warner <james.warner@comcast.net>

top/top.c

@@ -2728,17 +2728,21 @@ static void procs_hlp (proc_t *this) {
       case 'R':
          Frame_running++;
          break;
-      case 'S':
-      case 'D':
-         Frame_sleepin++;
-         break;
+      case 't':     // 't' (tracing stop)
       case 'T':
          Frame_stopped++;
          break;
       case 'Z':
          Frame_zombied++;
          break;
-      default:                    // keep gcc happy
+      default:
+         /* currently: 'D' (disk sleep),
+                       'I' (idle),
+                       'P' (parked),
+                       'S' (sleeping),
+                       'X' (dead - actually 'dying' & probably never seen)
+         */
+         Frame_sleepin++;
          break;
    }