De-memsetify Wii_SSL and fix segfault.

Fixes #7917
The first memset was clearing the delicate bits of the std::string in the struct, causing segfaults.

I also removed the rest of the memsets because they were paranoid, unneeded and wasteful. We shouldn't be managing the ssl libraries structs for it.
I checked and the ssl library's functions were already memsetting those structs as needed.
This is setting a field in a static array (https://github.com/phire/dolphin/blob/wii_ssl_segfault/Source/Core/Core/IPC_HLE/WII_IPC_HLE_Device_net_ssl.h#L86). If this class is constructed more than once, it'll trash the existing state. (Doesn't happen at the moment, but it'd nice for this to be enforced via code than convention).

If this class should be a singleton, it should have private constructor and this pattern: http://stackoverflow.com/a/11711991

Regardless, is there any reason that the WII_SSL array shouldn't be made an instance var of the class, and do this init in a (WII_SSL) constructor?