build: add rule to clean addon tests build

Add a `test-addons-clean` to the Makefile
to clean up files generated during testing addons.

PR-URL: nodejs#11519
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>

Makefile

@@ -358,6 +358,11 @@ test-npm-publish: $(NODE_EXE)
 test-addons: test-build
 	$(PYTHON) tools/test.py --mode=release addons
 
+test-addons-clean:
+	$(RM) -rf test/addons/??_*/
+	$(RM) -rf test/addons/*/build
+	$(RM) test/addons/.buildstamp test/addons/.docbuildstamp
+
 test-timers:
 	$(MAKE) --directory=tools faketime
 	$(PYTHON) tools/test.py --mode=release timers
@@ -857,10 +862,11 @@ endif
 
 .PHONY: lint cpplint jslint bench clean docopen docclean doc dist distclean \
 	check uninstall install install-includes install-bin all staticlib \
-	dynamiclib test test-all test-addons build-addons website-upload pkg \
-	blog blogclean tar binary release-only bench-http-simple bench-idle \
-	bench-all bench bench-misc bench-array bench-buffer bench-net \
-	bench-http bench-fs bench-tls cctest run-ci test-v8 test-v8-intl \
-	test-v8-benchmarks test-v8-all v8 lint-ci bench-ci jslint-ci doc-only \
-	$(TARBALL)-headers test-ci test-ci-native test-ci-js build-ci clear-stalled \
-	coverage-clean coverage-build coverage-test coverage list-gtests
+	dynamiclib test test-all test-addons test-addons-clean build-addons \
+	website-upload pkg blog blogclean tar binary release-only \
+	bench-http-simple bench-idle bench-all bench bench-misc bench-array \
+	bench-buffer bench-net bench-http bench-fs bench-tls cctest run-ci test-v8 \
+	test-v8-intl test-v8-benchmarks test-v8-all v8 lint-ci bench-ci jslint-ci \
+	doc-only $(TARBALL)-headers test-ci test-ci-native test-ci-js build-ci \
+	clear-stalled coverage-clean coverage-build coverage-test coverage \
+	list-gtests