[MIPS] Fix missing definitions for MIPS arch in build and driver scripts

pnacl/driver/driver_tools.py

 #!/usr/bin/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.
 #
 # IMPORTANT NOTE: If you make local mods to this file, you must run:
 #   %  pnacl/build.sh driver
 # in order for them to take effect in the scons build.  This command
 # updates the copy in the toolchain/ tree.
 #
@@ skipping 208 matching lines @@
 #
 ######################################################################
 
 DriverArgPatterns = [
   ( '--pnacl-driver-verbose',             "env.set('LOG_VERBOSE', '1')"),
   ( ('-arch', '(.+)'),                 "SetArch($0)"),
   ( '--pnacl-sb',                      "env.set('SANDBOXED', '1')"),
   ( '--pnacl-use-emulator',            "env.set('USE_EMULATOR', '1')"),
   ( '--dry-run',                       "env.set('DRY_RUN', '1')"),
   ( '--pnacl-arm-bias',                "env.set('BIAS', 'ARM')"),
+  ( '--pnacl-mips-bias',               "env.set('BIAS', 'MIPS32')"),
   ( '--pnacl-i686-bias',               "env.set('BIAS', 'X8632')"),
   ( '--pnacl-x86_64-bias',             "env.set('BIAS', 'X8664')"),
   ( '--pnacl-bias=(.+)',               "env.set('BIAS', FixArch($0))"),
   ( '--pnacl-default-command-line',    "env.set('USE_DEFAULT_CMD_LINE', '1')"),
   ( '-save-temps',                     "env.set('SAVE_TEMPS', '1')"),
   ( '-no-save-temps',                  "env.set('SAVE_TEMPS', '0')"),
  ]
 
 DriverArgPatternsNotInherited = [
   ( '--pnacl-driver-set-([^=]+)=(.*)',    "env.set($0, $1)"),
@@ skipping 701 matching lines @@
               'x86_64': 'X8664',
               'x86-64': 'X8664',
               'x8664' : 'X8664',
 
               'arm'   : 'ARM',
               'armv7' : 'ARM',
               'arm-thumb2' : 'ARM',
 
               'mips32': 'MIPS32',
               'mips'  : 'MIPS32',
+              'mipsel': 'MIPS32',
               }
   if arch not in archfix:
     Log.Fatal('Unrecognized arch "%s"!', arch)
   return archfix[arch]
 
 def IsWindowsPython():
   return 'windows' in platform.system().lower()
 
 def SetupCygwinLibs():
   bindir = env.getone('DRIVER_BIN')
@@ skipping 147 matching lines @@
         # Last step
         step_output = self.output
       else:
         # Intermediate step
         if self.use_names_for_input:
           step_output = self.namegen.TempNameForInput(self.input, output_type)
         else:
           step_output = self.namegen.TempNameForOutput(output_type)
       callback(step_input, step_output, **extra)
       step_input = step_output