This example requires that gr-audio-alsa be built in the main tree in order
to compile successfully.  It is not built automatically.

To build this example, you must make two modifications to the build system:

1) Add the following line inside config/grc_gnuradio_examples.m4:

   gnuradio-examples/c++/dial_tone/Makefile
   
   ...to the list of Makefiles already in there.
   
2) In gnuradio-examples/c++/Makefile.am, uncomment the SUBDIRS line

# SUBDIRS = dial_tone

Then, from the top-level directory, re-run ./bootstrap and ./configure.