x86 ptrace: remove long stale (and bitrotted) test for

PT_DTRACE without PT_PTRACED.

Long ago, the "D" in PT_DTRACE meant "Delayed", and it was used
as a flag to mark that we had ptrace'd the process but no longer
did so. That hasn't been true in a while now, and the flag should
probably be renamed, but in the meantime the test for PT_PTRACED
being cleared had been corrupted into something totally nonsensical.

Pointed out by Andi Kleen.

arch/i386/kernel/traps.c

@@ -725,8 +725,6 @@ fastcall void do_debug(struct pt_regs * regs, long error_code)
 		if (tsk->ptrace & PT_DTRACE) {
 			regs->eflags &= ~TF_MASK;
 			tsk->ptrace &= ~PT_DTRACE;
-			if (!tsk->ptrace & PT_DTRACE)
-				goto clear_TF;
 		}
 	}