Build with newer Boost. From Fedora.

Index: gr-qtgui/lib/histogram_sink_f_impl.cc
--- gr-qtgui/lib/histogram_sink_f_impl.cc.orig
+++ gr-qtgui/lib/histogram_sink_f_impl.cc
@@ -37,6 +37,8 @@
 namespace gr {
 namespace qtgui {
 
+using namespace boost::placeholders;
+
 histogram_sink_f::sptr histogram_sink_f::make(int size,
                                               int bins,
                                               double xmin,
