IAudioPolicyService, IAudioFlinger: check C structs on server side

Add more checks on C structs received on server side to avoid string
overflows in particular.
Move sanitization helpers into a specific class in media helper library.

Bug: 169572641
Test: audio smoke tests
Change-Id: I89cb840230c85dcdddd5b128f626bb4fe303832a
Merged-In: I89cb840230c85dcdddd5b128f626bb4fe303832a
diff --git a/media/libaudioclient/Android.bp b/media/libaudioclient/Android.bp
index 0c40cbb..fa2a159 100644
--- a/media/libaudioclient/Android.bp
+++ b/media/libaudioclient/Android.bp
@@ -63,6 +63,7 @@
 
         "AudioEffect.cpp",
         "AudioRecord.cpp",
+        "AudioSanitizer.cpp",
         "AudioSystem.cpp",
         "AudioTrack.cpp",
         "AudioTrackShared.cpp",