$(built_odex) depends on $(LOCAL_BUILT_MODULE) but doesn't have any build
recipe. It is built by the rules of $(LOCAL_BUILT_MODULE) that results in
a subtle bug: $(built_odex) is always newer than $(LOCAL_BUILT_MODULE)
if $(LOCAL_BUILT_MODULE) rebuilt. Therefore 'make' thinks the targets
(/system/app/$app.odex) depending on $(built_odex) don't need to be updated.
It seems an allegedly optimization bug of 'make'.
The simple fix is to explicitly add $(LOCAL_BUILT_MODULE) as a dependency
of $(installed_odex).
ifdef LOCAL_DEX_PREOPT
installed_odex := $(basename $(LOCAL_INSTALLED_MODULE)).odex
built_odex := $(basename $(LOCAL_BUILT_MODULE)).odex
-$(installed_odex) : $(built_odex) | $(ACP)
+$(installed_odex) : $(built_odex) $(LOCAL_BUILT_MODULE) | $(ACP)
@echo "Install: $@"
$(copy-file-to-target)