Remove emulator-based dexpreopt logic from the build system.

Change-Id: Ic96cbd1ebb9fa65aa85bf77f18a31913625d7e1c
diff --git a/core/main.mk b/core/main.mk
index 8a70489..81bebc8 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -224,9 +224,11 @@
   # TODO: Remove this and the corresponding block in
   # config/product_config.make once host-based Dalvik preoptimization is
   # working.
+  ifneq (true,$(DISABLE_DEXPREOPT))
   ifeq ($(HOST_OS)-$(WITH_DEXPREOPT_buildbot),linux-true)
     WITH_DEXPREOPT := true
   endif
+  endif
 
   # Disallow mock locations by default for user builds
   ADDITIONAL_DEFAULT_PROPERTIES += ro.allow.mock.location=0