test: support flaky tests in test-ci

Adding support for specifying flaky test mode to
the test runner:
- via an environment variable FLAKY_TESTS for Makefile
- via an argument ignore-flaky for vcbuild.bat

Ported from nodejs/node-v0.x-archive@2d2494c

PR-URL: nodejs#2424
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: João Reis <reis@janeasystems.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

Makefile

@@ -5,6 +5,7 @@ PYTHON ?= python
 DESTDIR ?=
 SIGN ?=
 PREFIX ?= /usr/local
+FLAKY_TESTS ?= run
 STAGINGSERVER ?= node-www
 
 OSTYPE := $(shell uname -s | tr '[A-Z]' '[a-z]')
@@ -140,7 +141,7 @@ test-all-valgrind: test-build
 	$(PYTHON) tools/test.py --mode=debug,release --valgrind
 
 test-ci: | build-addons
-	$(PYTHON) tools/test.py -p tap --logfile test.tap --mode=release \
+	$(PYTHON) tools/test.py -p tap --logfile test.tap --mode=release --flaky-tests=$(FLAKY_TESTS) \
 		addons message parallel sequential
 
 test-release: test-build

vcbuild.bat

@@ -70,6 +70,7 @@ if /i "%1"=="small-icu"     set i18n_arg=%1&goto arg-ok
 if /i "%1"=="full-icu"      set i18n_arg=%1&goto arg-ok
 if /i "%1"=="intl-none"     set i18n_arg=%1&goto arg-ok
 if /i "%1"=="download-all"  set download_arg="--download=all"&goto arg-ok
+if /i "%1"=="ignore-flaky"  set test_args=%test_args% --flaky-tests=dontcare&goto arg-ok
 
 echo Warning: ignoring invalid command line option `%1`.