[TESTS] add test-pollers.cfg to easily report pollers in use

tests/test-pollers.cfg

@@ -0,0 +1,15 @@
+# This is the smallest possible configuration. It does not
+# bind to any port, and is enough to check the polling
+# system in use without disturbing any running process.
+#
+# To be used that way:  haproxy -V -f test-pollers.cfg
+
+global
+	#nosepoll
+	#noepoll
+	#nopoll
+
+# fake backend to pass the config checks
+backend dummy
+	balance
+