Default package-modules to strict module checks

Every warning has been fixed on master now.

Test: multiproduct_kati (build_test through treehugger)
Change-Id: I5bbbb3bd330422f976cb13d9078c5e192f135dc4
diff --git a/core/tasks/tools/package-modules.mk b/core/tasks/tools/package-modules.mk
index 55a08f5..7c4266c 100644
--- a/core/tasks/tools/package-modules.mk
+++ b/core/tasks/tools/package-modules.mk
@@ -41,7 +41,7 @@
 ifeq ($(ALLOW_MISSING_DEPENDENCIES),true)
   # Ignore unknown installed files on partial builds
   my_missing_files =
-else ifeq ($(my_modules_strict),true)
+else ifneq ($(my_modules_strict),false)
   my_missing_files = $(shell $(call echo-error,$(my_makefile),$(my_package_name): Unknown installed file for module '$(1)'))$(eval my_missing_error := true)
 endif