Add some heursitics for compiling, close to Quick's.

Quick has more machinery to give up/not give up, but we can
backport them later.

Change-Id: I5eb62c664246f4ce46f0400cf24ec34a72afb51e
diff --git a/compiler/optimizing/builder.h b/compiler/optimizing/builder.h
index 25781b0..8519bcb 100644
--- a/compiler/optimizing/builder.h
+++ b/compiler/optimizing/builder.h
@@ -80,7 +80,13 @@
 
   // Finds all instructions that start a new block, and populates branch_targets_ with
   // the newly created blocks.
-  void ComputeBranchTargets(const uint16_t* start, const uint16_t* end);
+  // As a side effect, also compute the number of dex instructions, blocks, and
+  // branches.
+  void ComputeBranchTargets(const uint16_t* start,
+                            const uint16_t* end,
+                            size_t* number_of_dex_instructions,
+                            size_t* number_of_block,
+                            size_t* number_of_branches);
   void MaybeUpdateCurrentBlock(size_t index);
   HBasicBlock* FindBlockStartingAt(int32_t index) const;