In general, if a function generates output data like a msgb (or in this
case filling an osmo_oap_message structure), the output argument
precedes the source. This is what we use all over libosmo*, and it is
modelled after memcpy(), where dst is the first argument, before src.
Let's align osmo_oap_decode(). Intestingly, osmo_oap_encode was already
correct, so the encode/decode functions used different conventions
before.
Harald Welte
Neels Hofmeyr