Users are reporting a crash at the point where WiimoteAndroid::IORead
tries to use m_java_wiimote_payload. This commit solves the problem by
making m_java_wiimote_payload a global reference.
The code for setting up m_java_wiimote_payload has also been moved to
the constructor just because that way it's impossible for it to run
twice. (If the code as written were to run a second time, the old global
reference would be leaked. ConnectInternal should only run once, so this
is just to be on the safe side.)
Fixes https://bugs.dolphin-emu.org/issues/13960.