Mark typedefs as unused to fix build failure

runtime/vm/assembler_arm_test.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/os.h"
@@ skipping 670 matching lines @@
     __ tst(IP, Operand(0));
     __ b(&retry, NE);  // NE if context switch occurred between ldrex and strex.
     __ Pop(R0);  // 42
     __ bx(LR);
   }
 }
 
 
 ASSEMBLER_TEST_RUN(Semaphore, test) {
   EXPECT(test != NULL);
-  typedef int (*Semaphore)();
+  typedef int (*Semaphore)() DART_UNUSED;
   EXPECT_EQ(42, EXECUTE_TEST_CODE_INT32(Semaphore, test->entry()));
 }
 
 
 ASSEMBLER_TEST_GENERATE(FailedSemaphore, assembler) {
   if (TargetCPUFeatures::arm_version() == ARMv5TE) {
     __ mov(R0, Operand(41));
     __ bx(LR);
   } else {
     __ mov(R0, Operand(40));
     __ mov(R1, Operand(42));
     __ Push(R0);
     __ ldrex(R0, SP);
     __ clrex();  // Simulate a context switch.
     __ strex(IP, R1, SP);  // IP == 1, failure
     __ Pop(R0);  // 40
     __ add(R0, R0, Operand(IP));
     __ bx(LR);
   }
 }
 
 
 ASSEMBLER_TEST_RUN(FailedSemaphore, test) {
   EXPECT(test != NULL);
-  typedef int (*FailedSemaphore)();
+  typedef int (*FailedSemaphore)() DART_UNUSED;
   EXPECT_EQ(41, EXECUTE_TEST_CODE_INT32(FailedSemaphore, test->entry()));
 }
 
 
 ASSEMBLER_TEST_GENERATE(AddSub, assembler) {
   __ mov(R1, Operand(40));
   __ sub(R1, R1, Operand(2));
   __ add(R0, R1, Operand(4));
   __ rsbs(R0, R0, Operand(100));
   __ rsc(R0, R0, Operand(100));
@@ skipping 3401 matching lines @@
   __ StoreIntoObject(R2,
                      FieldAddress(R2, GrowableObjectArray::data_offset()),
                      R1);
   __ PopList((1 << CTX) | (1 << LR));
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM