Fix Chef unable to set audio-output through RPC #735

Job	Run time
Build framework (macos-release-availability, -sdk macosx -configuration Release OTHER_CFLAGS='$...	11m 44s
Build framework (ios-release, -sdk iphoneos -configuration Release OTHER_CFLAGS='${inherited} -We...	8m 54s
Build framework (ios-debug, -sdk iphoneos -configuration Debug OTHER_CFLAGS='${inherited} -Werr...	9m 24s
Build framework (tvos-debug, -sdk appletvos -configuration Debug OTHER_CFLAGS='${inherited} -Wer...	6m 43s
Run framework tests (asan, -enableAddressSanitizer YES -enableUndefinedBehaviorSanitizer YES)	24m 58s
Build TV Casting Bridge example	19m 14s
Build framework (watchos-debug, -sdk watchos -configuration Debug OTHER_CFLAGS='${inherited} -...	14m 53s
Run framework tests (asan-global-storage, -enableAddressSanitizer YES -enableUndefinedBehaviorSan...	19m 18s
Run framework tests (tsan, -enableThreadSanitizer YES)	19m 37s
Build Darwin	2s
	2h 14m 47s

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