Also add util/bot/golang to .gitignore.

I missed this one.

Change-Id: I642fb5878568870743727579126f63246ff179c5
Reviewed-on: https://boringssl-review.googlesource.com/12580
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/.gitignore b/.gitignore
index a04ecc1..9f396f6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@
 util/bot/cmake-mac.tar.gz
 util/bot/cmake-win32
 util/bot/cmake-win32.zip
+util/bot/golang
 util/bot/gyp
 util/bot/llvm-build
 util/bot/perl-win32