Fix android_media_AudioSystem_getMasterMute return type.

Caused FPU stack overflow on x86.

Bug: 18023418

(cherry picked from commit c1bcdbb75877d99972f1cd13a9c40126822621bc)

Change-Id: Ia1b5a1da52b20c2e0a84321e784cd795ec649e66
Merge "Fix android_media_AudioSystem_getMasterMute return type."