Fail when a non-vendor product references a vendor module.

Change-Id: Ia5ca233e9b11f64b72074f65899d3041cf955c4c
diff --git a/core/main.mk b/core/main.mk
index ac6442a..f76a8d1 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -622,12 +622,12 @@
 # and get rid of it from this list.
 # TODO: The shell is chosen by magic.  Do we still need this?
 modules_to_install := $(sort \
-        $(ALL_DEFAULT_INSTALLED_MODULES) \
-        $(product_MODULES) \
-        $(foreach tag,$(tags_to_install),$($(tag)_MODULES)) \
-        $(call get-tagged-modules, shell_$(TARGET_SHELL)) \
-        $(CUSTOM_MODULES) \
-    )
+    $(ALL_DEFAULT_INSTALLED_MODULES) \
+    $(product_MODULES) \
+    $(foreach tag,$(tags_to_install),$($(tag)_MODULES)) \
+    $(call get-tagged-modules, shell_$(TARGET_SHELL)) \
+    $(CUSTOM_MODULES) \
+  )
 
 # Some packages may override others using LOCAL_OVERRIDES_PACKAGES.
 # Filter out (do not install) any overridden packages.