"qemu/cutils.h" contains various qemu_strtosz_*() functions
useful to convert strings to size. It seems natural to have
the opposite usage (from size to string) there too.

The function definition is already in util/cutils.c.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20190903120555.7551-1-philmd@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>