util/qemu-error: Rename error_print_loc() to be more generic

Rename the error_print_loc() function in preparation for using it to
print warnings as well.

Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <661b215695db878a0aef8401b506fb3da50e981a.1499866456.git.alistair.francis@xilinx.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>