Makefile: Allow passing DOCKER_TEST_HOST and TESTDEBUG to container

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 968345bc5c0e3817d5d271124a2da11092e7447e)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Makefile

@@ -50,9 +50,11 @@ DOCKER_ENVS := \
 	-e DOCKER_PORT \
 	-e DOCKER_REMAP_ROOT \
 	-e DOCKER_STORAGE_OPTS \
+	-e DOCKER_TEST_HOST \
 	-e DOCKER_USERLANDPROXY \
 	-e DOCKERD_ARGS \
 	-e TEST_INTEGRATION_DIR \
+	-e TESTDEBUG \
 	-e TESTDIRS \
 	-e TESTFLAGS \
 	-e TIMEOUT \