Allow to build 10.6 binaries on Darwin x86_64 (the following binaries were actually built on such).

scripts/common.sh

 #!/bin/sh
 
 # Copyright (c) 2009-2010 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This script contains some functions useful to build
 # Valgrind and ThreadSanitizer for use with chromium
 
 THISDIR=$(dirname "${0}")
@@ skipping 157 matching lines @@
       else
         echo "You have Darwin kernel different from 9.X.X--11.X.X" >&2
         echo "Please, don't put the resulting binaries into Chromium SVN" >&2
         build_valgrind "local"
       fi
       ;;
     "Darwin x86_64")
       if system_is_lion
       then
         build_valgrind "mac_10.7"
+      elif system_is_snow_leopard
+      then
+        build_valgrind "mac_10.6" "--build=amd64-darwin"
       else
         echo "You have Darwin kernel different from 11.X.X" >&2
         echo "Please, don't put the resulting binaries into Chromium SVN" >&2
         build_valgrind "local"
       fi
       ;;
     *)
       build_valgrind "local"
       ;;
   esac
 }
 
 # Check that the binaries directory exists.
 BINARIES_DIR="$THISDIR/../binaries"
 if ! [ -a "$BINARIES_DIR" ]
 then
   echo "Error: $BINARIES_DIR doesn't exist!" >&2
   exit 1
 fi
 
 set -e
 set -x