Use only native engine & bitwriter LLVM libraries for linking.

Signed-off-by: José Fonseca <jfonseca@vmware.com>
diff --git a/scons/llvm.py b/scons/llvm.py
index 57fe922..916b040 100644
--- a/scons/llvm.py
+++ b/scons/llvm.py
@@ -166,7 +166,7 @@
                 pass
             env.MergeFlags(cppflags)
 
-            env.ParseConfig('llvm-config --libs')
+            env.ParseConfig('llvm-config --libs engine bitwriter')
             env.ParseConfig('llvm-config --ldflags')
         except OSError:
             print 'scons: llvm-config version %s failed' % llvm_version