Multilib support for odex

If the VM is libart and DEXPREOPT is enabled,
- For a Java library and the boot image, we build for both 1st arch and
  2nd arch.
- For an app, we build for the multilib arch the module is targeted for.
The odex file will be in <arch_name>/<module_name>.odex inside the same
dir where the jar/apk file gets installed.
Nothing changed if it's built for libdvm.

Bug: 14694978
Change-Id: I45118a83758b41d52d6c9e38f93f0ba2775a6c74