Add workaround to allow testing of ARM integrated assembler.

src/IceBuildDefs.h

 //===- subzero/src/IceBuildDefs.h - Translator build defines ----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// This file defines constexpr functions to query various #define values.
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICEBUILDDEFS_H
 #define SUBZERO_SRC_ICEBUILDDEFS_H
 
 namespace Ice {
 namespace BuildDefs {
 
 // The ALLOW_* etc. symbols must be #defined to zero or non-zero.
 constexpr bool disableIrGen() { return ALLOW_DISABLE_IR_GEN; }
 constexpr bool dump() { return ALLOW_DUMP; }
 constexpr bool llvmCl() { return ALLOW_LLVM_CL; }
 constexpr bool llvmIr() { return ALLOW_LLVM_IR; }
 constexpr bool llvmIrAsInput() { return ALLOW_LLVM_IR_AS_INPUT; }
 constexpr bool minimal() { return ALLOW_MINIMAL_BUILD; }
+constexpr bool checkIasmSafe() { return IASM_SAFE; }
 
 // NDEBUG can be undefined, or defined to something arbitrary.
 constexpr bool asserts() {
 #ifdef NDEBUG
   return false;
 #else  // !NDEBUG
   return true;
 #endif // !NDEBUG
 }
 
 // ALLOW_EXTRA_VALIDATION can be undefined, or defined to something non-zero.
 constexpr bool extraValidation() {
 #if ALLOW_EXTRA_VALIDATION
   return true;
 #else  // !ALLOW_EXTRA_VALIDATION
   return false;
 #endif // !ALLOW_EXTRA_VALIDATION
 }
 
 } // end of namespace BuildDefs
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEBUILDDEFS_H