ART: Generate switch targets from successor blocks

This patch relies on the successor blocks to generate switch targets
in GenSmallPackedSwitch and GenSmallSparseSwitch for all quick targets.
In x86, we create a new packed switch table by storing basic block
ids instead of dex offsets, and we override MarkPackedCaseLabels and
InsertCaseLabel to avoid calling FindBlock.

Change-Id: Ibb5983db582f0965aba787b520bd106522453564
Signed-off-by: Chao-ying Fu <chao-ying.fu@intel.com>