title: gdb stack strangeness
body: <p>I get this weird backtrace (sometimes):</p>
  
  <pre><code>(gdb) bt
  #0  0x00002b36465a5d4c in AY16_Loop_M16 () from /opt/intel/mkl/10.0.3.020/lib/em64t/libmkl_mc.so
  #1  0x00000000000021da in ?? ()
  #2  0x00000000000021da in ?? ()
  #3  0xbf3e9dec2f04aeff in ?? ()
  #4  0xbf480541bd29306a in ?? ()
  #5  0xbf3e6017955273e8 in ?? ()
  #6  0xbf442b937c2c1f37 in ?? ()
  #7  0x3f5580165832d744 in ?? ()
  ...
  </code></pre>
  
  <p>Any ideas why i cant see the symbols?  Compiled with debugging syms of course.
  The same session gives symbols at other points.</p>