Set jack.assert.policy value to 'always'

The policy value 'enable' does not exist anymore
and was replaced by 'always'

Change-Id: I233a555821a84d917e3b3ec923b5baffc18bd2d2
diff --git a/Android.mk b/Android.mk
index 568e200..9d44a6d 100644
--- a/Android.mk
+++ b/Android.mk
@@ -36,7 +36,7 @@
 
 # Only enable asserts on userdebug/eng builds
 ifneq (,$(filter userdebug eng, $(TARGET_BUILD_VARIANT)))
-LOCAL_JACK_FLAGS += -D jack.assert.policy=enable
+LOCAL_JACK_FLAGS += -D jack.assert.policy=always
 endif
 
 LOCAL_PACKAGE_NAME := DocumentsUI