Add math routines with defined wrapping behavior for the interpreter.

Add a RSUB_INT_LIT16 instruction alias to make instruction opcode switch
statements easier to read.

Change-Id: I3bac07c9518665abf0b05b5c3105a90be22f780a
diff --git a/runtime/verifier/method_verifier.cc b/runtime/verifier/method_verifier.cc
index 6e792d4..7380a50 100644
--- a/runtime/verifier/method_verifier.cc
+++ b/runtime/verifier/method_verifier.cc
@@ -2650,7 +2650,7 @@
                                          reg_types_.DoubleLo(), reg_types_.DoubleHi());
       break;
     case Instruction::ADD_INT_LIT16:
-    case Instruction::RSUB_INT:
+    case Instruction::RSUB_INT_LIT16:
     case Instruction::MUL_INT_LIT16:
     case Instruction::DIV_INT_LIT16:
     case Instruction::REM_INT_LIT16: