Add missing file

mk/tests.mk

+# Run program $1 as part of ‘make installcheck’.
+define run-install-test =
+
+  installcheck: $1
+
+  # Run the test in its own directory to mimick Automake behaviour.
+  $1.run: $1 $(_PREV_TEST)
+
+  _installcheck_list += $1
+
+endef
+
+installcheck: install
+	@total=0; failed=0; for i in $(_installcheck_list); do \
+	  total=$$((total + 1)); \
+	  echo "running test $$i"; \
+	  if (cd $$(dirname $$i) && $(TESTS_ENVIRONMENT) $$(basename $$i)); then \
+	    echo "PASS: $$i"; \
+	  else \
+	    echo "FAIL: $$i"; \
+	    failed=$$((failed + 1)); \
+	  fi; \
+	done; \
+	if [ "$$failed" != 0 ]; then \
+	  echo "$$failed out of $$total tests failed "; \
+	  exit 1; \
+	fi
+
+.PHONY: check installcheck