cmd/vendor/github.com/google/pprof: refresh from upstream

Updating to commit b1c91b9f8fa7647e4c43c96c50f245df551f7013
from github.com/google/pprof

Fixes #19342.

Change-Id: Iaaa283cdce3f9bf3e5fe713be7d23c477b579092
Reviewed-on: https://go-review.googlesource.com/37634
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/vendor/github.com/google/pprof/internal/driver/fetch_test.go

@@ -38,7 +38,7 @@ func TestSymbolizationPath(t *testing.T) {
 	}
 
 	// Save environment variables to restore after test
-	saveHome := os.Getenv("HOME")
+	saveHome := os.Getenv(homeEnv())
 	savePath := os.Getenv("PPROF_BINARY_PATH")
 
 	tempdir, err := ioutil.TempDir("", "home")
@@ -50,7 +50,7 @@ func TestSymbolizationPath(t *testing.T) {
 	os.Create(filepath.Join(tempdir, "pprof", "binaries", "abcde10001", "binary"))
 
 	obj := testObj{tempdir}
-	os.Setenv("HOME", tempdir)
+	os.Setenv(homeEnv(), tempdir)
 	for _, tc := range []struct {
 		env, file, buildID, want string
 		msgCount                 int
@@ -79,7 +79,7 @@ func TestSymbolizationPath(t *testing.T) {
 			t.Errorf("%s:%s:%s, want %s, got %s", tc.env, tc.file, tc.buildID, tc.want, file)
 		}
 	}
-	os.Setenv("HOME", saveHome)
+	os.Setenv(homeEnv(), saveHome)
 	os.Setenv("PPROF_BINARY_PATH", savePath)
 }
 

src/cmd/vendor/vendor.json

@@ -9,8 +9,8 @@
 		{
 			"canonical": "github.com/google/pprof",
 			"local": "github.com/google/pprof",
-			"revision": "e41fb7133e7ebb84ba6af2f6443032c728db26d3",
-			"revisionTime": "2017-03-01T00:04:42Z",
+			"revision": "b1c91b9f8fa7647e4c43c96c50f245df551f7013",
+			"revisionTime": "2017-03-01T17:36:15Z",
 		},
 		{
 			"canonical": "golang.org/x/arch/x86/x86asm",