Use shell to execute user_hardware via PATH

widgets/mainwindow.cpp

@@ -7943,7 +7943,7 @@ void MainWindow::WSPR_scheduling ()
       // to be anywhere in the paths specified in the PATH environment
       // variable  path list,  and  executable.  Equivalent to  typing
       // user_hardware without any path at the shell prompt.
-      p3.start("user_hardware", QStringList {band});
+      p3.start("/bin/sh", QStringList {"-c", "user_hardware " + band});
 #endif
 
       // Produce a short tuneup signal