Improve performance of call log.

Avoid binder calls in each layout pass by caching the results of
TelecomManager.getPhoneAccount() and TelecomManager.isVoiceMailNumber().
Do the latter by caching the actual voicemail number and doing the
comparison by ourselves.

Change-Id: I531cf7c9b3f0e99be8e1774605d6e0ee1ea229ab