Improve rules of split apks.

- Better messaging if the expected split apk isn't generated by the aapt
  command in the base apk rule; Remove the built base apk, so make will
  rerun aapt after the user changes the splitting parameters.
- Use cleaner static pattern rules instead of running $(foreach) with
  $(eval).

Bug: 16319961
Change-Id: If6ae302e1a39d2e0db8f784d4e1cf292ec855281