Initiate a constant propagation pass in the optimizing compiler.

- Perform constant folding on int and long additions and subtractions in
  the optimizing compiler.
- Apply constant folding to conditions and comparisons.

Change-Id: Ic88783a3c975fda777c74c531e257fa777be42eb
diff --git a/build/Android.gtest.mk b/build/Android.gtest.mk
index ac07721..3f58527 100644
--- a/build/Android.gtest.mk
+++ b/build/Android.gtest.mk
@@ -141,6 +141,7 @@
   compiler/oat_test.cc \
   compiler/optimizing/codegen_test.cc \
   compiler/optimizing/dead_code_elimination_test.cc \
+  compiler/optimizing/constant_propagation_test.cc \
   compiler/optimizing/dominator_test.cc \
   compiler/optimizing/find_loops_test.cc \
   compiler/optimizing/graph_checker_test.cc \