Re-add source-verify in cirrus-ci

Don't waste GCE VM resources for 30-min of testing,
when verify would fail after 3-minutes.  This is
the simpelest mechanism to save cloud CPU-time
while GCE is under trial-status (can not set quotas).

Signed-off-by: Chris Evich <cevich@redhat.com>

contrib/cirrus/verify_source.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+set -e
+source $(dirname $0)/lib.sh
+
+req_env_var "
+OS_RELEASE_ID $OS_RELEASE_ID
+OS_RELEASE_VER $OS_RELEASE_VER
+"
+
+show_env_vars
+
+set -x
+cd "$GOSRC"
+
+case "${OS_RELEASE_ID}-${OS_RELEASE_VER}" in
+    ubuntu-18)
+        make install.tools "BUILDTAGS=$BUILDTAGS"
+        make validate "BUILDTAGS=$BUILDTAGS"
+        # make lint "BUILDTAGS=$BUILDTAGS"
+        ;;
+    fedora-28) ;&
+    centos-7) ;&
+    rhel-7)
+        make install.tools
+        make validate
+        # make lint
+        ;;
+    *) bad_os_id_ver ;;
+esac