i#1551 Port DynamoRIO to ARM: fix release build error on arm/mangle.c
i#1551 Port DynamoRIO to ARM: fix release build error on arm/mangle.c

Review-URL: https://codereview.appspot.com/183590043

code4bones/dynamorio,daksunt/dynamorio,code4bones/dynamorio,sigma-random/dynamorio,AmesianX/dynamorio,code4bones/dynamorio,sigma-random/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,code4bones/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,sigma-random/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,bl4ckic3/dynamorio,bl4ckic3/dynamorio,sigma-random/dynamorio,code4bones/dynamorio,sigma-random/dynamorio,AmesianX/dynamorio,bl4ckic3/dynamorio,daksunt/dynamorio,AmesianX/dynamorio,daksunt/dynamorio