runtime/pprof: ignore CPU profile test failures in QEMU

Fixes #9605

Change-Id: Iafafa4c1362bbd1940f8e4fb979f72feae3ec3ad
Reviewed-on: https://go-review.googlesource.com/3000Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/runtime/pprof/pprof_test.go

@@ -10,6 +10,7 @@ import (
 	"bytes"
 	"fmt"
 	"math/big"
+	"os"
 	"os/exec"
 	"regexp"
 	"runtime"
@@ -186,6 +187,14 @@ func testCPUProfile(t *testing.T, need []string, f func()) {
 			t.Skipf("ignoring failure on %s; see golang.org/issue/6047", runtime.GOOS)
 			return
 		}
+		// Ignore the failure if the tests are running in a QEMU-based emulator,
+		// QEMU is not perfect at emulating everything.
+		// IN_QEMU environmental variable is set by some of the Go builders.
+		// IN_QEMU=1 indicates that the tests are running in QEMU. See issue 9605.
+		if os.Getenv("IN_QEMU") == "1" {
+			t.Skip("ignore the failure in QEMU; see golang.org/issue/9605")
+			return
+		}
 		t.FailNow()
 	}
 }