Remove the out of date comment, i.e., "# libqemu" since libqemu.a is not
available anymore.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Chen Wei-Ren <chenwj@iis.sinica.edu.tw>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>