== DETAILS
So, it turns out that there *is* a autoconfig disconnect handler. Took digging
through tasks/task_autodetect.c to find it!
So, I added a call to the handler when the pad gets disconnected.
This seems to solve the problem of the pad not disappearing from the menu.
(At the very least, the user's pad index reverts to "none" which is still
an improvement)
== TESTING
Tested manually, made sure it didn't crash or leak slots.
== DETAILS
The Wii U GC adapter doesn't seem to like doing async reads if it is connected
via a USB hub. It seems to be device-specific, though, because my DS3 works
just fine through the same hub.
I tried creating a fallback to synchronous reads, but it resulted in a hard
lock of the system. So, for the time being, it's going to be a known
limitation. Might be solved by using a powered USB hub.
Learned that the cache alignment is 64, not 32, so the alignment math has
been updated. Thanks, @aliaspider for that info.
This should fix the issue where R/L buttons didn't register when doing
input detection.
This also brings the GC pad in line with the rest of the gamepads in
input_autodetect_builtin.c.
Also fixed a really stupid bug that was part of why analog inputs aren't
being read. Analog still isn't working, mind, but it's a lot closer to
working now that it's actually getting down into the pad driver level!
=== DETAILS
So, the GCA has 2 USB connections; one is the data connection, and the
second is used to drive rumble.
Due to a driver bug, if the second cable wasn't attached, the pads wouldn't
get detected.
I fixed that bug.
