Build with newer Boost. From Fedora.

Index: gr-qtgui/lib/sink_f_impl.cc
--- gr-qtgui/lib/sink_f_impl.cc.orig
+++ gr-qtgui/lib/sink_f_impl.cc
@@ -36,6 +36,8 @@
 namespace gr {
 namespace qtgui {
 
+using namespace boost::placeholders;
+
 sink_f::sptr sink_f::make(int fftsize,
                           int wintype,
                           double fc,
