Only enable WITH_DEXPREOPT by default for libdvm.so

Bug: 14298175

(cherry picked from commit 9f8e214a91)

Change-Id: I96ba4e198b7bc1b7d9a502c432590f41c87d05c4

core/main.mk

@@ -334,13 +334,15 @@ ifneq (,$(user_variant))
     enable_target_debugging :=
   endif
 
-  # Turn on Dalvik preoptimization for user builds, but only if not
+  # Turn on Dalvik preoptimization for libdvm.so user builds, but only if not
   # explicitly disabled and the build is running on Linux (since host
   # Dalvik isn't built for non-Linux hosts).
   ifeq (,$(WITH_DEXPREOPT))
-    ifeq ($(user_variant),user)
-      ifeq ($(HOST_OS),linux)
-        WITH_DEXPREOPT := true
+    ifeq ($(DALVIK_VM_LIB),libdvm.so)
+      ifeq ($(user_variant),user)
+        ifeq ($(HOST_OS),linux)
+          WITH_DEXPREOPT := true
+        endif
       endif
     endif
   endif