Fix Windows deprecation warnings using WideCharToMultiByte() #209

Job	Run time
Tarball	58s
Linux (jack, JACK, jack=enabled, libjack-dev)	1m 21s
MacOS	2m 29s
Linux (alsa, ALSA, alsa=enabled, libasound-dev)	45s
MinGW (i686-w64-mingw32, dsound)	52s
Linux (pulse, PULSE, pulse=enabled, libpulse-dev)	1m 14s
MinGW (x86_64-w64-mingw32, dsound)	1m 7s
MinGW (i686-w64-mingw32, asio, -Wno-unused-but-set-variable)	58s
MinGW (x86_64-w64-mingw32, asio, -Wno-unused-but-set-variable)	1m 2s
Linux (oss, OSS, oss=true, oss4-dev)	48s
MinGW (i686-w64-mingw32, wasapi)	52s
MinGW (x86_64-w64-mingw32, wasapi)	54s
	13m 20s

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