qemu_strtoi64() assumes int64_t is long long.  This is marked FIXME.
Replace by a QEMU_BUILD_BUG_ON() to avoid surprises.

Same for qemu_strtou64().

Fix a typo in qemu_strtoul()'s contract while there.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20191125133846.27790-2-armbru@redhat.com>
[lv: removed trailing whitespace]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>