Debugger: Don't hard code /usr/bin/gdbserver

Just requiring it to be in $PATH is more flexible and helps e.g.
in cases where /usr is physically read-only on the device and
no or an unsuitable gdbserver is present.

Task-number: QTCREATORBUG-8705
Change-Id: I07bb30dbcc55ecc4c89d4dfda8a873197da43604
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/debugger/gdb/startgdbserverdialog.cpp

@@ -122,7 +122,7 @@ void GdbServerStarter::portListReady()
     connect(&d->runner, SIGNAL(readyReadStandardError()), SLOT(handleProcessErrorOutput()));
     connect(&d->runner, SIGNAL(processClosed(int)), SLOT(handleProcessClosed(int)));
 
-    QByteArray cmd = "/usr/bin/gdbserver --attach :"
+    QByteArray cmd = "gdbserver --attach :"
             + QByteArray::number(port) + ' ' + QByteArray::number(d->process.pid);
     logMessage(tr("Running command: %1").arg(QString::fromLatin1(cmd)));
     d->runner.run(cmd, d->device->sshParameters());