I had to apply this patch to get the library to build after your change:
commit 0f1151f651987ba6772959c49c5afc6898dd9e83
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Apr 22 21:20:03 2013 -0400
* src/c++11/hashtable_c++0x.cc: Include ext/aligned_buffer.h.
diff --git a/libstdc++-v3/src/c++11/hashtable_c++0x.cc b/libstdc++-v3/src/c++11/hashtable_c++0x.cc
index 7617c58..bddb7ff 100644
--- a/libstdc++-v3/src/c++11/hashtable_c++0x.cc
+++ b/libstdc++-v3/src/c++11/hashtable_c++0x.cc
@@ -28,6 +28,7 @@
#include <initializer_list>
#include <tuple>
+#include <ext/aligned_buffer.h>
#include <bits/hashtable_policy.h>
namespace std _GLIBCXX_VISIBILITY(default)
