Update FreeBSD 12 slaves to a newer image

FreeBSD's 12-current is the development branch and hence has binary incompatible
changes from time to time. So update the base image to reflect the recent changes
and again be compatible with the binary packes for that system.

Also readd freebsd-12 to the build tests. Fixes #77.

Change-Id: I2a5d23ce8d586436ffb6aeb971209b951b7957d8
diff --git a/gce/vm.sh b/gce/vm.sh
index e66f69f..752e507 100755
--- a/gce/vm.sh
+++ b/gce/vm.sh
@@ -54,7 +54,7 @@
     "ubuntu-docker-slave-1 https://www.googleapis.com/compute/v1/projects/ubuntu-os-cloud/global/images/ubuntu-1510-wily-v20151026 ubuntu_15.10-x86_64-docker-1 europe-west1-d default startup-script=jenkins-slave.sh ubuntu-15-10-slave.sh ubuntu-15-10-docker.sh bootstrap-bazel.sh linux-android.sh cleanup-install.sh"
     "ubuntu-docker-slave-2 https://www.googleapis.com/compute/v1/projects/ubuntu-os-cloud/global/images/ubuntu-1510-wily-v20151026 ubuntu_15.10-x86_64-docker-2 europe-west1-d default startup-script=jenkins-slave.sh ubuntu-15-10-slave.sh ubuntu-15-10-docker.sh bootstrap-bazel.sh linux-android.sh cleanup-install.sh"
     "freebsd-11-slave https://www.googleapis.com/compute/v1/projects/freebsd-org-cloud-dev/global/images/freebsd-11-0-stable-amd64-2017-01-06 freebsd-11-1 europe-west1-d default startup-script=jenkins-slave.sh freebsd-slave.sh freebsd-ci-homedir.sh"
-    "freebsd-12-slave https://www.googleapis.com/compute/v1/projects/freebsd-org-cloud-dev/global/images/freebsd-12-0-current-amd64-2017-01-06 freebsd-12-1 europe-west1-d default startup-script=jenkins-slave.sh freebsd-slave.sh freebsd-ci-homedir.sh"
+    "freebsd-12-slave https://www.googleapis.com/compute/v1/projects/freebsd-org-cloud-dev/global/images/freebsd-12-0-current-amd64-2017-06-02 freebsd-12-1 europe-west1-d default startup-script=jenkins-slave.sh freebsd-slave.sh freebsd-ci-homedir.sh"
     # Fow Windows, we use a custom image with pre-installed MSVC.
     "windows-slave-1 windows-server-2012-r2-dc-v20160112-vs2015-cpp-python-msys windows-x86_64-1 europe-west1-d default windows-startup-script-ps1=jenkins-slave-windows.ps1"
     "windows-slave-2 windows-server-2012-r2-dc-v20160112-vs2015-cpp-python-msys windows-x86_64-2 europe-west1-d default windows-startup-script-ps1=jenkins-slave-windows.ps1"
@@ -90,7 +90,7 @@
     "ubuntu-16-04-slave-staging ubuntu-1604-lts ubuntu_16.04-x86_64-staging europe-west1-d staging startup-script=jenkins-slave.sh ubuntu-16-04-slave.sh bootstrap-bazel.sh linux-android.sh cleanup-install.sh"
     "ubuntu-docker-slave-staging https://www.googleapis.com/compute/v1/projects/ubuntu-os-cloud/global/images/ubuntu-1510-wily-v20151026 ubuntu_15.10-x86_64-docker-staging europe-west1-d staging startup-script=jenkins-slave.sh ubuntu-15-10-slave.sh ubuntu-15-10-docker.sh bootstrap-bazel.sh linux-android.sh cleanup-install.sh"
     "freebsd-11-slave-staging https://www.googleapis.com/compute/v1/projects/freebsd-org-cloud-dev/global/images/freebsd-11-0-stable-amd64-2017-01-06 freebsd-11-staging europe-west1-d staging startup-script=jenkins-slave.sh freebsd-slave.sh freebsd-ci-homedir.sh"
-    "freebsd-12-slave-staging https://www.googleapis.com/compute/v1/projects/freebsd-org-cloud-dev/global/images/freebsd-12-0-current-amd64-2017-01-06 freebsd-12-staging europe-west1-d staging startup-script=jenkins-slave.sh freebsd-slave.sh freebsd-ci-homedir.sh"
+    "freebsd-12-slave-staging https://www.googleapis.com/compute/v1/projects/freebsd-org-cloud-dev/global/images/freebsd-12-0-current-amd64-2017-06-02 freebsd-12-staging europe-west1-d staging startup-script=jenkins-slave.sh freebsd-slave.sh freebsd-ci-homedir.sh"
     # Fow Windows, we use a custom image with pre-installed MSVC.
     "windows-slave-staging windows-server-2012-r2-dc-v20160112-vs2015-cpp-python-msys windows-x86_64-staging europe-west1-d staging windows-startup-script-ps1=jenkins-slave-windows.ps1"
     "windows-msvc-slave-staging windows-server-2012-r2-dc-v20160112-vs2015-cpp-python-msys windows-msvc-x86_64-staging europe-west1-d staging windows-startup-script-ps1=jenkins-slave-windows-msvc.ps1"
diff --git a/jenkins/jobs/jobs.bzl b/jenkins/jobs/jobs.bzl
index f147af5..4c6138d 100644
--- a/jenkins/jobs/jobs.bzl
+++ b/jenkins/jobs/jobs.bzl
@@ -3,9 +3,7 @@
     "ubuntu_16.04-x86_64",
 ]
 
-# TODO(#77): renable freebsd-12 when it works properly.
-#BSD_PLATFORMS = ["freebsd-11", "freebsd-12"]
-BSD_PLATFORMS = ["freebsd-11"]
+BSD_PLATFORMS = ["freebsd-11", "freebsd-12"]
 
 DARWIN_PLATFORMS = ["darwin-x86_64"]