Adds support for ARM softfp calling convention.

tools/build.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012, 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.
 #
 
 import optparse
 import os
 import re
@@ skipping 101 matching lines @@
         return False
       if 'v8' in args:
         print "The v8 target is not supported for android builds."
         return False
   return True
 
 
 def SetTools(arch, toolchainprefix):
   toolsOverride = None
   if arch == 'arm' and toolchainprefix == None:
+    # Here, we specify the hf compiler. If this changes, we must also remove
+    # the ARM_FLOAT_ABI_HARD define in configurations_make.gypi.
     toolchainprefix = (DEFAULT_ARM_CROSS_COMPILER_PATH +
                        "/bin/arm-linux-gnueabihf")
   if toolchainprefix:
     toolsOverride = {
       "CC.target"  :  toolchainprefix + "-gcc",
       "CXX.target" :  toolchainprefix + "-g++",
       "AR.target"  :  toolchainprefix + "-ar",
       "LINK.target":  toolchainprefix + "-g++",
       "NM.target"  :  toolchainprefix + "-nm",
     }
@@ skipping 317 matching lines @@
           process.wait()
           if process.returncode != 0:
             print "BUILD FAILED"
             return 1
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(Main())