Reordered includes to be consistent with the LLVM style.

llvm-svn: 7887
diff --git a/llvm/include/Support/HashExtras.h b/llvm/include/Support/HashExtras.h
index f644cbd..44355a4 100644
--- a/llvm/include/Support/HashExtras.h
+++ b/llvm/include/Support/HashExtras.h
@@ -10,8 +10,8 @@
 #ifndef SUPPORT_HASHEXTRAS_H
 #define SUPPORT_HASHEXTRAS_H
 
-#include <string>
 #include "Support/hash_map"
+#include <string>
 
 // Cannot specialize hash template from outside of the std namespace.
 namespace HASH_NAMESPACE {