Include autoconf test for google's sparsehash

configure.ac

@@ -256,7 +256,6 @@ AC_CHECK_HEADER([CGAL/version.h],
                 [AC_MSG_ERROR([CGAL headers not found])])
 
 
-
 dnl cairo
 if test "$USING_CAIRO" = "yes"; then
    PKG_CHECK_MODULES(CAIROMM, [cairomm-1.0], AC_DEFINE([HAVE_CAIROMM], [1],
@@ -274,6 +273,13 @@ if test "$USING_CAIRO" = "yes"; then
    [CPPFLAGS="${OLD_CPPFLAGS}"]
 fi
 
+dnl sparsehash
+dnl set template depth and hidden visibility
+[CPPFLAGS="${CPPFLAGS} -I/usr/include/sparsehash -I/usr/include/google"]
+AC_CHECK_HEADER([dense_hash_set],
+                [],
+                [AC_MSG_ERROR([sparsehash headers not found])])
+
 dnl Checks for typedefs, structures, and compiler characteristics.
 dnl Checks for library functions.
 

src/graph/community/graph_blockmodel.cc

@@ -34,6 +34,7 @@
 
 #include "random.hh"
 
+#include "config.h"
 #include "graph_blockmodel.hh"
 
 using namespace boost;

src/graph/community/graph_blockmodel.hh

@@ -32,8 +32,8 @@ using __gnu_cxx::power;
 #   include <boost/tr1/tuple.hpp>
 #  endif
 
-#include <sparsehash/dense_hash_set>
-#include <sparsehash/dense_hash_map>
+#include <dense_hash_set>
+#include <dense_hash_map>
 
 namespace graph_tool
 {