Add mock bundle logic in makefile

In the CI we can run the release target using mock
bundles which will help us to detect any issue due to changes
in release target.

.travis.yml

@@ -9,3 +9,5 @@ script:
 - make cross-lint
 - make cross
 - make test
+- alias podman=docker
+- make BUNDLE_DIR=/tmp MOCK_BUNDLE=true release

Makefile

@@ -45,6 +45,8 @@ SOURCES := $(shell git ls-files  *.go ":^vendor")
 
 RELEASE_INFO := release-info.json
 
+MOCK_BUNDLE ?= false
+
 # Check that given variables are set and all have non-empty values,
 # die with an error otherwise.
 #
@@ -195,6 +197,9 @@ LIBVIRT_BUNDLENAME = $(BUNDLE_DIR)/crc_libvirt_$(BUNDLE_VERSION).$(BUNDLE_EXTENS
 
 .PHONY: embed_bundle check_bundledir
 check_bundledir:
+ifeq ($(MOCK_BUNDLE),true)
+	touch $(HYPERKIT_BUNDLENAME) $(HYPERV_BUNDLENAME) $(LIBVIRT_BUNDLENAME)
+endif
 	@$(call check_defined, BUNDLE_DIR, "Embedding bundle requires BUNDLE_DIR set to a directory containing CRC bundles for all hypervisors")
 
 embed_bundle: LDFLAGS += $(BUNDLE_EMBEDDED)