Don't block on STDIN open

This was found testing other runtime shims that are faster than runc(no
containerization).  This is a race that can cause the shim to block
forever.  It's not an issue for out/err because we open both sides of
the pipe, but for stdin, it expects the client to have it opened.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

runtime/v1/linux/proc/exec.go

@@ -164,10 +164,7 @@ func (e *execProcess) start(ctx context.Context) (err error) {
 		return e.parent.runtimeError(err, "OCI runtime exec failed")
 	}
 	if e.stdio.Stdin != "" {
-		fifoCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
-		defer cancel()
-
-		sc, err := fifo.OpenFifo(fifoCtx, e.stdio.Stdin, syscall.O_WRONLY|syscall.O_NONBLOCK, 0)
+		sc, err := fifo.OpenFifo(ctx, e.stdio.Stdin, syscall.O_WRONLY|syscall.O_NONBLOCK, 0)
 		if err != nil {
 			return errors.Wrapf(err, "failed to open stdin fifo %s", e.stdio.Stdin)
 		}
@@ -184,10 +181,7 @@ func (e *execProcess) start(ctx context.Context) (err error) {
 			return errors.Wrap(err, "failed to start console copy")
 		}
 	} else if !e.stdio.IsNull() {
-		fifoCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
-		defer cancel()
-
-		if err := copyPipes(fifoCtx, e.io, e.stdio.Stdin, e.stdio.Stdout, e.stdio.Stderr, &e.wg, &copyWaitGroup); err != nil {
+		if err := copyPipes(ctx, e.io, e.stdio.Stdin, e.stdio.Stdout, e.stdio.Stderr, &e.wg, &copyWaitGroup); err != nil {
 			return errors.Wrap(err, "failed to start io pipe copy")
 		}
 	}