package/go: bump version to 1.12.8

go1.12.6 (released 2019/06/11) includes fixes to the compiler, the linker, the
go command, and the crypto/x509, net/http, and os packages.

go1.12.7 (released 2019/07/08) includes fixes to cgo, the compiler, and the
linker.

go1.12.8 (released 2019/08/13) includes security fixes to the net/http and
net/url packages.

https://golang.org/doc/devel/release.html

Signed-off-by: Christian Stewart <christian@paral.in>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 81b164c537e8078f3c3a3eb374496dcc1e930dea)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/go/go.hash

@@ -1,3 +1,3 @@
 # From https://golang.org/dl/
-sha256	2aa5f088cbb332e73fc3def546800616b38d3bfe6b8713b8a6404060f22503e8  go1.12.5.src.tar.gz
+sha256	11ad2e2e31ff63fcf8a2bdffbe9bfa2e1845653358daed593c8c2d03453c9898  go1.12.8.src.tar.gz
 sha256	2d36597f7117c38b006835ae7f537487207d8ec407aa9d9980794b2030cbc067  LICENSE

package/go/go.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-GO_VERSION = 1.12.5
+GO_VERSION = 1.12.8
 GO_SITE = https://storage.googleapis.com/golang
 GO_SOURCE = go$(GO_VERSION).src.tar.gz