Convert stderr message calling error_get_pretty() to error_report()

Convert stderr message calling error_get_pretty() to error_report()

Convert stderr messages calling error_get_pretty()
to error_report().

Timestamp is prepended by -msg timstamp option with it.

Per Markus's comment below, A conversion from fprintf() to
error_report() is always an improvement, regardless of
error_get_pretty().

http://marc.info/?l=qemu-devel&m=137513283408601&w=2

But, it is not reasonable to convert them at one time
because fprintf() is used everwhere in qemu.

So, it should be done step by step with avoiding regression.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>