wget: add support for https using "openssl s_client" as a helper

www.kernel.org started redirecting http:// to https://
making https support mandatory for any auto build scripts.

function                                             old     new   delta
wget_main                                           2631    2971    +340
parse_url                                            409     471     +62
.rodata                                           115607  115626     +19
P_HTTPS                                                -       6      +6
P_HTTP                                                 -       5      +5
P_FTP                                                  -       4      +4
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(add/remove: 3/0 grow/shrink: 3/0 up/down: 436/0)             Total: 436 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>