package/go: bump version to 1.12.9

For post-1.12.8 fixes. From the release notes:

go1.12.9 (released 2019/08/15) includes fixes to the linker, and the os and
math/big packages.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
diff --git a/package/go/go.hash b/package/go/go.hash
index acf4686..a4820ee 100644
--- a/package/go/go.hash
+++ b/package/go/go.hash
@@ -1,3 +1,3 @@
 # From https://golang.org/dl/
-sha256	11ad2e2e31ff63fcf8a2bdffbe9bfa2e1845653358daed593c8c2d03453c9898  go1.12.8.src.tar.gz
+sha256	ab0e56ed9c4732a653ed22e232652709afbf573e710f56a07f7fdeca578d62fc  go1.12.9.src.tar.gz
 sha256	2d36597f7117c38b006835ae7f537487207d8ec407aa9d9980794b2030cbc067  LICENSE
diff --git a/package/go/go.mk b/package/go/go.mk
index fecd5f0..9b7263a 100644
--- a/package/go/go.mk
+++ b/package/go/go.mk
@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-GO_VERSION = 1.12.8
+GO_VERSION = 1.12.9
 GO_SITE = https://storage.googleapis.com/golang
 GO_SOURCE = go$(GO_VERSION).src.tar.gz