wget: make the ssl variant provides wget-ssl

wget: make the ssl variant provides wget-ssl

This is to address the need for specifying dependency on a wget
implementation with ssl support.

Now we have a game of names for opkg

 1. uclient-fetch: minimal version by openwrt project
 2. wget-nossl: gnu wget w/o ssl support
 3. wget-ssl: for the moment since this commit, gnu wget w/ ssl support
 4. wget: uclient-fetch, wget-nossl, or wget-ssl
 5. gnu-wget: wget-nossl or wget-ssl

By the time we provide some dummy package like uclient-fetch-ssl and
make it also provide wget-ssl, I guess by then we will also need
gnu-wget-ssl...

Ref: https://github.com/openwrt/packages/issues/11534
Ref: https://github.com/openwrt/packages/pull/9941
Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>