[cirrus-ci] Removing pkg -y update and using 11.3-snap instead of 11.2 (#2018)

* Replacing with boilerplate from cirrus

* Adding task name and adding back freebsd 11.x

* Changing from 11.3 to freebsd-11-3-snap

* Rearanging the order of matrix and instance

.cirrus.yml

@@ -1,16 +1,11 @@
-env:
-  CIRRUS_CLONE_DEPTH: 1
-  ARCH: amd64
-
 task:
+  name: FreeBSD (shortest)
   freebsd_instance:
     matrix:
-      image: freebsd-12-0-release-amd64
-      image: freebsd-11-2-release-amd64
-  install_script:
-    - sed -i.bak -e 's,pkg+http://pkg.FreeBSD.org/\${ABI}/quarterly,pkg+http://pkg.FreeBSD.org/\${ABI}/latest,' /etc/pkg/FreeBSD.conf
-    - pkg upgrade -y
-    - pkg install -y gmake coreutils
+      image_family: freebsd-12-1
+      # The stable 11.3 image causes "Agent is not responding" so use a snapshot
+      image_family: freebsd-11-3-snap
+  install_script: pkg install -y gmake coreutils
   script: |
     MOREFLAGS="-Werror" gmake -j all
     gmake shortest