Add binutils support for build_tc.py.

This is part 1 of the work. Another part involves modification to
binutils ebuild file, which will be done after upgrading to
binutils-2.22.

Ahmad has made a really good framework, so the modification here is pretty straight forward.

PRESUBMIT=passed
BUG=None
R=asharif,llozano
CC=bjanakiraman,carrot,cmtice
APPROVED=asharif
OCL=65462-p2
RCL=65479-p2
RDATE=2013/01/28 10:08:58
TEST=./build_tc.py --binutils_dir=/usr/local/google/home/shenhan/hdd2/live-binutils-2.22/src/third_party/binutils --chromeos_root=/usr/local/google/home/shenhan/hdd2/live --board=x86-alex


P4 change: 42806378
diff --git a/v14/build_tc.py b/v14/build_tc.py
index 6f82e89..7084b99 100755
--- a/v14/build_tc.py
+++ b/v14/build_tc.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python2.6
+#!/usr/bin/python
 #
 # Copyright 2010 Google Inc. All Rights Reserved.
 
@@ -169,6 +169,9 @@
                     "--gcc_dir",
                     dest="gcc_dir",
                     help="The directory where gcc resides.")
+  parser.add_option("--binutils_dir",
+                    dest="binutils_dir",
+                    help="The directory where binutils resides.")
   parser.add_option("-x",
                     "--gdb_dir",
                     dest="gdb_dir",
@@ -222,6 +225,8 @@
   chromeos_root = misc.CanonicalizePath(options.chromeos_root)
   if options.gcc_dir:
     gcc_dir = misc.CanonicalizePath(options.gcc_dir)
+  if options.binutils_dir:
+    binutils_dir = misc.CanonicalizePath(options.binutils_dir)
   if options.gdb_dir:
     gdb_dir = misc.CanonicalizePath(options.gdb_dir)
   if options.unmount_only:
@@ -253,6 +258,10 @@
       tp = ToolchainPart("gcc", gcc_dir, chromeos_root, board,
                          not options.noincremental, build_env)
       toolchain_parts.append(tp)
+    if options.binutils_dir:
+      tp = ToolchainPart("binutils", binutils_dir, chromeos_root, board,
+                         not options.noincremental, build_env)
+      toolchain_parts.append(tp)
     if options.gdb_dir:
       tp = ToolchainPart("gdb", gdb_dir, chromeos_root, board,
                          not options.noincremental, build_env)