go_1_9: 1.9.4 -> 1.9.5

This is a maintenance bump of the golang 1.9 version.

Within the updates are a few bug fixes including an (extended?)
fix for CVE-2018-7187 [1].

The complete changelog is available at the golang GitHub project [2].

[1] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-7187
[2] https://github.com/golang/go/issues?q=milestone%3AGo1.9.5

(cherry picked from commit e9f74b91d6f0d6997ee25cae6d100e6ba4b3a6eb)

pkgs/development/compilers/go/1.9.nix

···
 
 stdenv.mkDerivation rec {
   name = "go-${version}";
-  version = "1.9.4";
+  version = "1.9.5";
 
   src = fetchFromGitHub {
     owner = "golang";
     repo = "go";
     rev = "go${version}";
-    sha256 = "15d9lfiy1cjfz6nqnig5884ykqckx58cynd1bva1xna7bwcwwp2r";
+    sha256 = "15dx1b71xv7b265gqk9nv02pirggpw7d83apikhrza2qkj64ydd0";
   };
 
   # perl is used for testing go vet