string: Correctly burn the string buffer.
string: Correctly burn the string buffer.

Signed-off-by: Andreas Schneider <5be00ddc76278cf6077f5047ca3384a88460c671@cryptomilk.org>
Reviewed-by: Aris Adamantiadis <78e305742ac743ecf22d8139502576ac8709e0ad@0xbadc0de.be>
(cherry picked from commit 1ddb99c46ffbeeac52f27a630b50670848b39e0c)

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