Updated build-gnuradio

One of my users in Guatemala found an issue with the build-gnuradio
script. If your system is configured for anything other
than English, the script fails, because it’s parsing the output of
“ls -l”, and looking for a “Not found” error message. Which of
course, will only happen if the systems message library is set for
English. Fixed. Who knew?

Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium