Adjust pnacl-translate sbtc flag override mechanism to append.

SConstruct

 #! -*- python -*-
 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import atexit
 import os
 import platform
 import re
 import subprocess
@@ skipping 1089 matching lines @@
 # (arch, subarch) pair
 AVAILABLE_PLATFORMS = {
     'x86-32'      : { 'arch' : 'x86' , 'subarch' : '32' },
     'x86-64'      : { 'arch' : 'x86' , 'subarch' : '64' },
     'mips32'      : { 'arch' : 'mips', 'subarch' : '32' },
     'arm'         : { 'arch' : 'arm' , 'subarch' : '32' },
     'arm-thumb2'  : { 'arch' : 'arm' , 'subarch' : '32' }
     }
 
 # Look up the platform name from the command line arguments.
-def GetPlatform():
+def GetPlatform(self):
   return ARGUMENTS.get('platform', 'x86-32')
 
+pre_base_env.AddMethod(GetPlatform)
 
 # Decode platform into list [ ARCHITECTURE , EXEC_MODE ].
 def DecodePlatform(platform):
   if platform in AVAILABLE_PLATFORMS:
     return AVAILABLE_PLATFORMS[platform]
   raise Exception('Unrecognized platform: %s' % platform)
 
 
 DeclareBit('build_x86_32', 'Building binaries for the x86-32 architecture',
            exclusive_groups='build_arch')
@@ skipping 22 matching lines @@
 DeclareBit('build_x86', 'Building binaries for the x86 architecture')
 DeclareBit('target_x86', 'Tools being built will process x86 binaries')
 
 # Shorthand for either arm or thumb2 versions of ARM
 DeclareBit('build_arm', 'Building binaries for the arm architecture')
 DeclareBit('target_arm', 'Tools being built will process arm binaries')
 
 
 def MakeArchSpecificEnv():
   env = pre_base_env.Clone()
-  platform = GetPlatform()
+  platform = env.GetPlatform()
   info = DecodePlatform(platform)
 
   env.Replace(BUILD_FULLARCH=platform)
   env.Replace(BUILD_ARCHITECTURE=info['arch'])
   env.Replace(BUILD_SUBARCH=info['subarch'])
   env.Replace(TARGET_FULLARCH=platform)
   env.Replace(TARGET_ARCHITECTURE=info['arch'])
   env.Replace(TARGET_SUBARCH=info['subarch'])
 
   # Example: PlatformBit('build', 'x86-32') -> build_x86_32
   def PlatformBit(prefix, platform):
     return "%s_%s" % (prefix, platform.replace('-', '_'))
 
   env.SetBits(PlatformBit('build', platform))
   env.SetBits(PlatformBit('target', platform))
 
   if env.Bit('build_x86_32') or env.Bit('build_x86_64'):
     env.SetBits('build_x86')
   if env.Bit('build_arm_arm') or env.Bit('build_arm_thumb2'):
     env.SetBits('build_arm')
 
   if env.Bit('target_x86_32') or env.Bit('target_x86_64'):
     env.SetBits('target_x86')
   if env.Bit('target_arm_arm') or env.Bit('target_arm_thumb2'):
     env.SetBits('target_arm')
 
-  env.Replace(BUILD_ISA_NAME=GetPlatform())
+  env.Replace(BUILD_ISA_NAME=env.GetPlatform())
 
   if env.Bit('target_arm') or env.Bit('target_mips32'):
     if not env.Bit('native_code'):
       # This is a silent default on ARM and MIPS.
       env.SetBits('bitcode')
 
   # If it's not bitcode, it's native code.
   if not env.Bit('bitcode'):
     env.SetBits('native_code')
 
@@ skipping 1533 matching lines @@
   elif linux_env.Bit('build_x86_64'):
     linux_env.Prepend(
         CCFLAGS = ['-m64'],
         LINKFLAGS = ['-m64'],
         )
   elif linux_env.Bit('build_arm'):
     SetupLinuxEnvArm(linux_env)
   elif linux_env.Bit('build_mips32'):
     SetupLinuxEnvMips(linux_env)
   else:
-    Banner('Strange platform: %s' % GetPlatform())
+    Banner('Strange platform: %s' % env.GetPlatform())
 
   # These are desireable options for every Linux platform:
   # _FORTIFY_SOURCE: general paranoia "hardening" option for library functions
   # -fPIE/-pie: create a position-independent executable
   # relro/now: "hardening" options for linking
   # noexecstack: ensure that the executable does not get a PT_GNU_STACK
   #              header that causes the kernel to set the READ_IMPLIES_EXEC
   #              personality flag, which disables NX page protection.
   linux_env.Prepend(
       CPPDEFINES=[['-D_FORTIFY_SOURCE', '2']],
@@ skipping 737 matching lines @@
     # The ComponentProgram method (site_scons/site_tools/component_builders.py)
     # adds dependencies on env['IMPLICIT_LIBS'] if that's set.
     if env.Bit('bitcode'):
       implicit_libs += ['libnacl.a']
     else:
       implicit_libs += ['crt1.o',
                         'libnacl.a',
                         'crti.o',
                         'crtn.o']
       # TODO(mcgrathr): multilib nonsense defeats -B!  figure out a better way.
-      if GetPlatform() == 'x86-32':
+      if env.GetPlatform() == 'x86-32':
         implicit_libs.append(os.path.join('32', 'crt1.o'))
 
   if implicit_libs != []:
     env['IMPLICIT_LIBS'] = [env.File(os.path.join('${LIB_DIR}', file))
                             for file in implicit_libs]
     # The -B<dir>/ flag is necessary to tell gcc to look for crt[1in].o there.
     env.Prepend(LINKFLAGS=['-B${LIB_DIR}/'])
 
 AddImplicitLibs(nacl_env)
 AddImplicitLibs(nacl_irt_env)
@@ skipping 266 matching lines @@
   nacl_env.ValidateSdk()
 
 if BROKEN_TEST_COUNT > 0:
   msg = "There are %d broken tests." % BROKEN_TEST_COUNT
   if GetOption('brief_comstr'):
     msg += " Add --verbose to the command line for more information."
   print msg
 
 # separate warnings from actual build output
 Banner('B U I L D - O U T P U T:')