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

Update vendored pprof to commit 4fc39a00b6b8c1aad05260f01429ec70e127252c
from github.com/google/pprof (2017-11-01).

Fixes #19380
Updates #21047

Change-Id: Ib64a94a45209039e5945acbcfa0392790c8ee41e
Reviewed-on: https://go-review.googlesource.com/57370
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/src/cmd/vendor/github.com/google/pprof/CONTRIBUTING.md b/src/cmd/vendor/github.com/google/pprof/CONTRIBUTING.md
new file mode 100644
index 0000000000..5976686d73
--- /dev/null
+++ b/src/cmd/vendor/github.com/google/pprof/CONTRIBUTING.md
@@ -0,0 +1,27 @@
+Want to contribute? Great! First, read this page (including the small print at the end).
+
+### Before you contribute
+
+Before we can use your code, you must sign the
+[Google Individual Contributor License Agreement](https://cla.developers.google.com/about/google-individual)
+(CLA), which you can do online. The CLA is necessary mainly because you own the
+copyright to your changes, even after your contribution becomes part of our
+codebase, so we need your permission to use and distribute your code. We also
+need to be sure of various other things—for instance that you'll tell us if you
+know that your code infringes on other people's patents. You don't have to sign
+the CLA until after you've submitted your code for review and a member has
+approved it, but you must do it before we can put your code into our codebase.
+Before you start working on a larger contribution, you should get in touch with
+us first through the issue tracker with your idea so that we can help out and
+possibly guide you. Coordinating up front makes it much easier to avoid
+frustration later on.
+
+### Code reviews
+
+All submissions, including submissions by project members, require review.  
+We use Github pull requests for this purpose.
+
+### The small print
+
+Contributions made by corporations are covered by a different agreement than the one above,  
+the [Software Grant and Corporate Contributor License Agreement](https://cla.developers.google.com/about/google-corporate).