Re-add VOLUME_MOUNTS, remove CLEAN var

Signed-off-by: Eli Uriegas <eli.uriegas@docker.com>

Author: seemethere

Makefile

@@ -1,9 +1,10 @@
 TEST_IMAGE?=ubuntu:18.04
 VERSION?=
 CHANNEL?=
+
+VOLUME_MOUNTS=-v "$(CURDIR)":/v
 SHELLCHECK_EXCLUSIONS=$(addprefix -e, SC1091 SC1117 SC2188)
 SHELLCHECK=docker run --rm -v "$(CURDIR)":/v -w /v koalaman/shellcheck $(SHELLCHECK_EXCLUSIONS)
-CLEAN := *~
 
 ENVSUBST_VARS=LOAD_SCRIPT_COMMIT_SHA HTML