all: fix plan9 failures

Updates golang/go#11811

Change-Id: I6ed252eb3272354fce8084ec99f4777e41c3daa3
Reviewed-on: https://go-review.googlesource.com/18993
Reviewed-by: Chris Broadfoot <cbro@golang.org>

cmd/godoc/godoc_test.go

@@ -44,7 +44,9 @@ var godocTests = []struct {
 	{
 		args: []string{"nonexistingpkg"},
 		matches: []string{
-			`no such file or directory|does not exist|cannot find the file`,
+			// The last pattern (does not e) is for plan9:
+			// http://build.golang.org/log/2d8e5e14ed365bfa434b37ec0338cd9e6f8dd9bf
+			`no such file or directory|does not exist|cannot find the file|(?:' does not e)`,
 		},
 	},
 	{

cmd/stress/stress.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !plan9
+
 // The stress utility is intended for catching of episodic failures.
 // It runs a given process in parallel in a loop and collects any failures.
 // Usage:

go/ssa/interp/external_plan9.go

@@ -6,6 +6,9 @@ package interp
 
 import "syscall"
 
+func ext۰os۰Pipe(fr *frame, args []value) value {
+	panic("os.Pipe not yet implemented")
+}
 func ext۰syscall۰Close(fr *frame, args []value) value {
 	panic("syscall.Close not yet implemented")
 }