title: Make gdb search for symbol files again
body: <p>My distribution (Debian) ships debug files in separate packages. So what happens often is that I run a program in <code>gdb</code> until it crashes, in order to obtain a usable backtrace for a bug report. But <code>bt</code> is rather useless, missing the symbol information – because I did not install the corresponding <code>-dbg</code> package.</p>
  
  <p>If I install the package now, is there a way to make <code>gdb</code> search for the symbol files again, without losing my current backtrace?</p>