Implement the -am argument to allow choosing an AUTH method.
For now only PLAIN and LOGIN are supported, but others can be added
easily in the future.
AUTH PLAIN required adding a new variant of encode_base64() capable of
handling NUL characters in the input string; the old function is now a
wrapper for the newer one.
function old new delta
encode_n_base64 - 236 +236
sendmail_main 1199 1380 +181
packed_usage 32873 32877 +4
encode_base64 242 36 -206
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(add/remove: 1/0 grow/shrink: 2/1 up/down: 421/-206) Total: 215 bytes
Signed-off-by: Raffaello D. Di Napoli <rafdev@dinapo.li>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
