Remove MIPS support

runtime/vm/atomic_linux.h

 // 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.
 
 #ifndef RUNTIME_VM_ATOMIC_LINUX_H_
 #define RUNTIME_VM_ATOMIC_LINUX_H_
 
 #if !defined RUNTIME_VM_ATOMIC_H_
 #error Do not include atomic_linux.h directly. Use atomic.h instead.
 #endif
@@ skipping 14 matching lines @@
   return __sync_fetch_and_add(p, 1);
 }
 
 
 inline void AtomicOperations::IncrementBy(intptr_t* p, intptr_t value) {
   __sync_fetch_and_add(p, value);
 }
 
 
 inline void AtomicOperations::IncrementInt64By(int64_t* p, int64_t value) {
-#if defined(TARGET_ARCH_MIPS)
-  // No double-word atomics on MIPS32.
-  *p += value;
-#else
   __sync_fetch_and_add(p, value);
-#endif
 }
 
 
 inline uintptr_t AtomicOperations::FetchAndDecrement(uintptr_t* p) {
   return __sync_fetch_and_sub(p, 1);
 }
 
 
 inline intptr_t AtomicOperations::FetchAndDecrement(intptr_t* p) {
   return __sync_fetch_and_sub(p, 1);
@@ skipping 16 matching lines @@
 inline uint32_t AtomicOperations::CompareAndSwapUint32(uint32_t* ptr,
                                                        uint32_t old_value,
                                                        uint32_t new_value) {
   return __sync_val_compare_and_swap(ptr, old_value, new_value);
 }
 #endif  // !defined(USING_SIMULATOR_ATOMICS)
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_ATOMIC_LINUX_H_