scons: Also link in additional LLVM components.

They don't seem necessary here, but they shouldn't hurt either...
diff --git a/SConstruct b/SConstruct
index 7f9a222..7e7f515 100644
--- a/SConstruct
+++ b/SConstruct
@@ -133,7 +133,7 @@
 # LLVM
 if llvm:
 	# See also http://www.scons.org/wiki/UsingPkgConfig
-	env.ParseConfig('llvm-config --cflags --ldflags --libs backend bitreader engine ipo')
+	env.ParseConfig('llvm-config --cflags --ldflags --libs backend bitreader engine instrumentation interpreter ipo')
 	env.Append(CPPDEFINES = ['MESA_LLVM'])
         # Force C++ linkage
 	env['LINK'] = env['CXX']