PNaCl: Add more MIPS support to the toolchain

pnacl/driver/pnacl-as.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.
 #
 
 import driver_tools
 from driver_env import env
 from driver_log import Log, TempFiles
 import sys
 
 EXTRA_ENV = {
   'INPUTS'      : '',
   'OUTPUT'      : '',
 
   'MC_FLAGS'       : '-assemble -filetype=obj ${MC_FLAGS_%ARCH%}',
   # maybe add the equivalent of -mfpu=vfp
   'MC_FLAGS_ARM'   : '-arch=arm -triple=armv7a-nacl -mcpu=cortex-a8',
   'MC_FLAGS_X8632' : '-arch=x86 -triple=i686-nacl',
   'MC_FLAGS_X8664' : '-arch=x86-64 -triple=x86_64-nacl',
+  'MC_FLAGS_MIPS32': '-arch=mipsel -triple=mipsel-nacl',
 
   'RUN_LLVM_AS'    : '${LLVM_AS} ${input} -o ${output}',
   'RUN_LLVM_MC'    : '${LLVM_MC} ${MC_FLAGS} ${input} -o ${output}',
 }
 
 VERSION_STR = """Portable Native Client assembler
 Compatibility:
 GNU assembler version 2.21.51 (pnacl-pc-nacl) using BFD version (GNU Binutils) 2.21.51.20110525
 Low Level Virtual Machine (http://llvm.org/)
 """
@@ skipping 78 matching lines @@
 Transform LLVM assembly (.ll) to LLVM bitcode.
 
 Usage: pnacl-as [options] <input .ll file> -o <output.po>
 
 OPTIONS:
   -o <file>        Output to file
   --version        Display version information
   -help | -h       Output this help.
 """