golang: v↑ go1.16 (1.16 -> 1.16.2)

Going Go1.16 -> Go1.16.2 brings in fixes to compiler, runtime and stdlib
including security fixes to archive/zip and encoding/xml:

https://golang.org/doc/devel/release.html#go1.16.minor

Tested on helloworld SR.

component/golang/buildout.cfg

@@ -71,8 +71,8 @@ environment-extra =
 
 [golang1.16]
 <= golang-common
-url = https://golang.org/dl/go1.16.src.tar.gz
-md5sum = b767f7e81d886b4208874ea953db2ce3
+url = https://golang.org/dl/go1.16.2.src.tar.gz
+md5sum = 516f63e11c64b1984045c035d4c2f65d
 
 # go1.16 needs go1.4 to bootstrap
 environment-extra =