Add atomic-counter to testsuite

Fixes #79

ci/config.sh

@@ -228,6 +228,7 @@ case "$BUILD_MODE" in
         test_package all "$(pwd)/../tests/text"
         test_package bytestring-tests "$(pwd)/../tests/bytestring"
         test_package all "$(pwd)/../tests/containers/containers-tests"
+        test_package test "$(pwd)/../tests/atomic-counter"
         ;;
     COMPAT)
         test_package system-test "$(pwd)/../tests/ghc-debug/**/*.cabal"