gui: ENABLE_BLUEZ=OFF: bluetooth/bluetooth.h uneeded

[mazes-80]

Use case: packaging cemu for gentoo users (WIP)

ENABLE_BLUEZ=OFF should prevent using bluetooth under linux.
However wxgui still expose some:
#include <bluetooth/bluetooth.h>

To be able to compile I just used

sed -i -e '/input\/PairingDialog/d' src/gui/wxgui/CMakeLists.txt
sed -i -e '/auto\* pairingDialog/,/sizer->Add(pairingDialog/d;' \
       -e '/include.*PairingDialog/d' src/gui/wxgui/input/InputSettings2.cpp

This early PR based on local work I did when upgrading package but uses build system logic