Fixing v8 build when include or lib are set.

v8/build.scons

 # Copyright 2009, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
@@ skipping 75 matching lines @@
   v8_env['ENV']['VSCOMNTOOLS'] = env.subst('$VC80_DIR/Common7/Tools')
 
   # SCons crashes if USERPROFILE isn't defined, and it's not defined
   # on Vista for some reason, so this is to make the Vista build work.
   try:
     v8_env['ENV']['USERPROFILE'] = os.environ['USERPROFILE']
   except KeyError:
     v8_env['ENV']['USERPROFILE'] = ""
 
   include_path = ";".join(
-    [v8_env.subst("$INCLUDE"),
-     v8_env.subst("$PLATFORM_SDK_VISTA_6_0_DIR/Include")])
+    [v8_env.subst("$PLATFORM_SDK_VISTA_6_0_DIR/Include"),
+     v8_env.subst("$INCLUDE")])
 
   try:
-    v8_env['ENV']['INCLUDE'] += ";" + include_path
+    v8_env['ENV']['INCLUDE'] = include_path + ";" + v8_env['ENV']['INCLUDE']
   except KeyError:
     v8_env['ENV']['INCLUDE'] = include_path
 
   lib_path = ";".join(
-    [v8_env.subst("$LIB"),
-     v8_env.subst("$PLATFORM_SDK_VISTA_6_0_DIR/Lib")])
+    [v8_env.subst("$PLATFORM_SDK_VISTA_6_0_DIR/Lib"),
+     v8_env.subst("$LIB")])
 
   try:
-    v8_env['ENV']['LIB'] += ";" + lib_path
+    v8_env['ENV']['LIB'] =  lib_path  + ";" + v8_env['ENV']['LIB']
   except KeyError:
     v8_env['ENV']['LIB'] = lib_path
 
 v8_no_snapshot = v8_env.Command(
     v8_scons_targets_no_snapshot,
     [],
     ['$V8_SCONS_COM msvcltcg=off snapshot=off sample=shell'])
 
 v8_snapshot = v8_env.Command(
     v8_scons_targets_snapshot,
     [],
     ['$V8_SCONS_COM msvcltcg=off snapshot=on'])
 
 v8_env.AlwaysBuild(v8_no_snapshot)
 v8_env.AlwaysBuild(v8_snapshot)
 
 # Tell our SCons invocation to *not* delete v8.lib and the other targets
 # before building them, so the subsidiary v8 SCons call doesn't always
 # rebuild them (thereby causing us to always rebuild their dependents).
 v8_env.Precious(v8_no_snapshot)
 v8_env.Precious(v8_snapshot)
 
 v8_env.Install('$LIB_DIR', v8_lib)