Add a public key entry
#include <libssh2.h>
int libssh2_publickey_add_ex(LIBSSH2_PUBLICKEY *pkey, const unsigned char *name,
unsigned long name_len, const unsigned char *blob, unsigned long blob_len, char overwrite, unsigned long num_attrs, const libssh2_publickey_attribute attrs[])
TBD
Returns 0 on success, negative on failure.
LIBSSH2_ERROR_BAD_USE LIBSSH2_ERROR_ALLOC, LIBSSH2_ERROR_EAGAIN LIBSSH2_ERROR_SOCKET_SEND, LIBSSH2_ERROR_SOCKET_TIMEOUT, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL,