Disable multithreaded dexopt by default

* There is still a race condition here.
* Power users can re-enable this by setting
  persist.sys.dalvik.multithread to true

Change-Id: I03686bafbac1859695466fcb522bc5436ec82e0d

config/common.mk

@@ -66,6 +66,10 @@ PRODUCT_PROPERTY_OVERRIDES += \
 PRODUCT_PROPERTY_OVERRIDES += \
     ro.build.selinux=1
 
+# Disable multithreaded dexopt by default
+PRODUCT_PROPERTY_OVERRIDES += \
+    persist.sys.dalvik.multithread=false
+
 # Thank you, please drive thru!
 PRODUCT_PROPERTY_OVERRIDES += persist.sys.dun.override=0