vendor: globally enable dexpreopt

This can be opted out by including in the device's BoardConfigOmni.mk file:

        WITH_DEXPREOPT := false

Individual apps can be excluded by either adding the following the the app's makefile:

        LOCAL_DEX_PREOPT := false

or by adding the following to the device's omni_device.mk:

        $(call add-product-dexpreopt-module-config,modulename,disable)

Change-Id: Ib8561632c1f0fa5aac4c65cf2c818396d3d149a1
diff --git a/config/common.mk b/config/common.mk
index 5194026..2dff26e 100644
--- a/config/common.mk
+++ b/config/common.mk
@@ -71,3 +71,8 @@
 
 # Add our overlays
 PRODUCT_PACKAGE_OVERLAYS += vendor/omni/overlay/common
+
+# Enable dexpreopt for all nightlies
+ifeq ($(ROM_BUILDTYPE),NIGHTLY)
+    WITH_DEXPREOPT := TRUE
+endif