utils: Add declaration back for osmo_osmo_hexdump_nospc

As it turns out, if a project uses the old name but without a declaration,
it'll causes a segfault on 64 bits platform (because of the implicit
int return type which doesn't apply since here it's a pointer).

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
1 file changed