Split the rules to build the odex file

Previously the odex file is byproduct generated by the package.apk rule.
Though we have the odex file depend on the package.apk it doesn't have
its own build recipe. In case package.apk isn't updated but we still
need to update the odex file (such as changed LOCAL_MULTILIB), the odex
file will never be rebuilt.
This change split out the rules to build the odex file and make sure the
build recipe get executed if the odex file needs rebuild.

Change-Id: I60c2f32b536b3d59045301ee863aae1451734aad