Update Golang 1.12.15

Update Golang 1.12.15
-------------------------------

full diff: golang/go@go1.12.14...go1.12.15

go1.12.15 (released 2020/01/09) includes fixes to the runtime and the net/http
package. See the Go 1.12.15 milestone on the issue tracker for details:

https://github.com/golang/go/issues?q=milestone%3AGo1.12.15+label%3ACherryPickApproved

Update Golang 1.12.14
-------------------------------

go1.12.14 (released 2019/12/04) includes a fix to the runtime. See the Go 1.12.14
milestone on our issue tracker for details:

https://github.com/golang/go/issues?q=milestone%3AGo1.12.14+label%3ACherryPickApproved

Update Golang 1.12.13
-------------------------------

go1.12.13 (released 2019/10/31) fixes an issue on macOS 10.15 Catalina where the
non-notarized installer and binaries were being rejected by Gatekeeper. Only macOS
users who hit this issue need to update.

Signed-off-by: Sebastiaan van Stijn <[email protected]>

Author: thaJeztah

common.mk

@@ -2,7 +2,7 @@ ARCH=$(shell uname -m)
 BUILDTIME=$(shell date -u -d "@$${SOURCE_DATE_EPOCH:-$$(date +%s)}" --rfc-3339 ns 2> /dev/null | sed -e 's/ /T/')
 DEFAULT_PRODUCT_LICENSE:=Community Engine
 DOCKER_GITCOMMIT:=abcdefg
-GO_VERSION:=1.12.12
+GO_VERSION:=1.12.15
 PLATFORM=Docker Engine - Community
 SHELL:=/bin/bash
 VERSION?=0.0.0-dev