Make use of AIDL unions.

Now that AIDL supports proper unions, use those instead of the struct-
of-arrays workaround.

Change-Id: Ie4753254dcdeab7dec5075e83fccbb1226895ba9
diff --git a/media/libaudioclient/AudioSystem.cpp b/media/libaudioclient/AudioSystem.cpp
index 8a91e3b..cfe5f3a 100644
--- a/media/libaudioclient/AudioSystem.cpp
+++ b/media/libaudioclient/AudioSystem.cpp
@@ -36,7 +36,7 @@
 #define VALUE_OR_RETURN_STATUS(x) \
     ({ auto _tmp = (x); \
        if (!_tmp.ok()) return Status::fromStatusT(_tmp.error()); \
-       _tmp.value(); })
+       std::move(_tmp.value()); })
 
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