Add support for preopted app images

Enable iff WITH_DEXPREOPT_APP_IMAGE is true.

Test: Clean + build with the flag on and off. Tested Sailfish
booting.

Bug: 34927277

(cherry picked from commit e8ab2a71d7bff1047c3d0497feba6bdcc02b8277)

Change-Id: I63f98a85c69d99746b11bb6e85c23cf5e48910cf
diff --git a/core/product.mk b/core/product.mk
index 93d42fd..7d7c68b 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -289,7 +289,8 @@
 _product_stash_var_list += \
 	DEFAULT_SYSTEM_DEV_CERTIFICATE \
 	WITH_DEXPREOPT \
-	WITH_DEXPREOPT_BOOT_IMG_ONLY
+	WITH_DEXPREOPT_BOOT_IMG_ONLY \
+	WITH_DEXPREOPT_APP_IMAGE
 
 #
 # Mark the variables in _product_stash_var_list as readonly