Introduce per-product per-module dex-preopt config

- Added LOCAL_DEX_PREOPT_FLAGS to pass extra flags to dex2oat.
- Added macro add-product-dex-preopt-module-config to specify almost
  arbitrary dex-preopt config/flags to modules in product
  configuration:
  $(call \
  add-product-dex-preopt-module-config,<module_name_list>,<config_or_flags>)
  How <config_or_flags> is interpreted is decided by
  dex_preopt_odex_install.mk and dex2oat. For now if it's "disable" we
  disable dexpreopt for the given modules; otherwise pass it to dex2oat as
  command line flags.
- If there are multiple configs for the same module in the product
  inheritance, the first takes precedence.
- Added PRODUCT_DEX_PREOPT_DEFAULT_FLAGS so you can specify default
  dex2oat flags in product configuration.
- Added PRODUCT_DEX_PREOPT_BOOT_FLAGS to specify flags of building boot.oat.

Bug: 17791867
Change-Id: I1b2955e8e51039e94d1ff43a3265a8d03598632c

Conflicts:
	core/product.mk