scons: add more LIBS for compiling with LLVM 2.9 on Windows

These extra libs shouldn't hurt with LLVM 2.8 or older.
diff --git a/scons/llvm.py b/scons/llvm.py
index c8d2d37..57fe922 100644
--- a/scons/llvm.py
+++ b/scons/llvm.py
@@ -135,6 +135,8 @@
         env.Append(LIBS = [
             'imagehlp',
             'psapi',
+            'shell32',
+            'advapi32'
         ])
         if env['msvc']:
             # Some of the LLVM C headers use the inline keyword without