messages: use predefined macro for clearing sensitive data
messages: use predefined macro for clearing sensitive data

Signed-off-by: Luka Perkov <fe6d8aafe911b69ec3eecb89e7941038c0d25a22@sartura.hr>
Reviewed-by: Andreas Schneider <5be00ddc76278cf6077f5047ca3384a88460c671@cryptomilk.org>
(cherry picked from commit a2fe341da558d27c348d55b1fbf9824f42ff2432)

mwgoldsmith/ssh,mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/ssh