[dev.boringcrypto] misc/boring: add go1.12.6b4 and go1.11.11b4 releases
[dev.boringcrypto] misc/boring: add go1.12.6b4 and go1.11.11b4 releases

Change-Id: I90b79a5519f92bb56370e11fd47c06dabaf845e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/182338
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>

golang/go,nawawi/go,golang/go,golang/go,nawawi/go,golang/go,nawawi/go,nawawi/go,nawawi/go,golang/go,nawawi/go,nawawi/go,golang/go,golang/go,golang/go,nawawi/go