[BT] Add keepalive frame every 3 sec for Switch ctrls #367

Job	Run time
build (hw1, 3do)	3m 15s
build (hw1, cdi)	3m 30s
build (hw1, dreamcast)	3m 22s
build (hw1, gamecube)	4m 0s
build (hw1, gbahd)	3m 55s
build (hw1, genesis)	3m 56s
build (hw1, jaguar)	3m 23s
build (hw1, jvs_arcade)	3m 30s
build (hw1, n64)	4m 11s
build (hw1, nes)	3m 33s
build (hw1, parallel_1p)	3m 22s
build (hw1, parallel_1p_3v3)	3m 31s
build (hw1, parallel_2p)	3m 21s
build (hw1, parallel_2p_3v3)	3m 17s
build (hw1, pc_engine)	3m 50s
build (hw1, pcfx)	3m 25s
build (hw1, playstation)	3m 23s
build (hw1, saturn)	3m 26s
build (hw1, snes)	3m 17s
build (hw1, universal)	3m 34s
build (hw1, virtualboy)	3m 54s
build (hw1, wii_extension)	3m 21s
build (hw2, 3do)	3m 30s
build (hw2, cdi)	3m 24s
build (hw2, dreamcast)	3m 28s
build (hw2, gamecube)	3m 30s
build (hw2, gbahd)	3m 56s
build (hw2, genesis)	3m 48s
build (hw2, jaguar)	3m 52s
build (hw2, jvs_arcade)	3m 24s
build (hw2, n64)	3m 21s
build (hw2, nes)	3m 58s
build (hw2, parallel_1p)	3m 16s
build (hw2, parallel_1p_3v3)	3m 24s
build (hw2, parallel_2p)	3m 19s
build (hw2, parallel_2p_3v3)	3m 26s
build (hw2, pc_engine)	3m 25s
build (hw2, pcfx)	3m 20s
build (hw2, playstation)	3m 50s
build (hw2, saturn)	3m 20s
build (hw2, snes)	3m 40s
build (hw2, universal)	3m 47s
build (hw2, virtualboy)	3m 28s
build (hw2, wii_extension)	3m 34s
build (dbg, pad_test)	3m 18s
build (dbg, qemu)	3m 18s
build (dbg, qemu_bt_trace_replay)	3m 52s
build (dbg, qemu_bt_trace_replay_test)	3m 23s
	2h 50m 7s

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