golang: v↑ (1.6.3)

From upcoming https://golang.org/doc/devel/release.html#go1.6.minor

    go1.6.3 (released 2016/07/17) includes security fixes to the net/http/cgi
    package and net/http package when used in a CGI environment. This release also
    adds support for macOS Sierra.  See the Go 1.6.3 milestone[1] on our issue
    tracker for details.

    [1] https://github.com/golang/go/issues?q=milestone%3AGo1.6.3

/reviewed-by TrustMe    (tested with helloworld)

component/golang/buildout.cfg

@@ -36,8 +36,8 @@ environment-extra =
 
 [golang16]
 <= golang-common
-url = https://storage.googleapis.com/golang/go1.6.2.src.tar.gz
-md5sum = d1b50fa98d9a71eeee829051411e6207
+url = https://storage.googleapis.com/golang/go1.6.3.src.tar.gz
+md5sum = bf3fce6ccaadd310159c9e874220e2a2
 
 # go1.6 needs go1.4 to bootstrap
 environment-extra =