DBC: Adds simdbc64 target, adds arm64 arithmetic overflow logic

tools/gyp/configurations_make.gypi

 # Copyright (c) 2011, 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.
 
 {
   'variables': {
     'dart_debug_optimization_level%': '2',
   },
   'target_defaults': {
     'configurations': {
@@ skipping 101 matching lines @@
           '-m64',
         ],
       },
 
       'Dart_Linux_simdbc_Base': {
         'abstract': 1,
         'cflags': [ '-O3', '-m32', '-msse2', '-mfpmath=sse' ],
         'ldflags': [ '-m32', ],
       },
 
+      'Dart_Linux_simdbc64_Base': {
+        'abstract': 1,
+        'cflags': [ '-O3', '-m64', '-msse2', '-mfpmath=sse' ],
+        'ldflags': [ '-m64', ],
+      },
+
       # ARM cross-build
       'Dart_Linux_xarm_Base': {
         'abstract': 1,
         'target_conditions': [
         ['_toolset=="target"', {
           'cflags': [
             '-marm',
             '-mfpu=vfp',
             '-Wno-psabi', # suppresses va_list warning
             '-fno-strict-overflow',
@@ skipping 211 matching lines @@
           '-ffunction-sections',
           '-fomit-frame-pointer',
         ],
         'ldflags': [
           '-Wl,--gc-sections',
         ],
       },
     },
   },
 }