Convert IEffect and IEffectClient to AIDL

This change replaces the manually-parceled IEffect and IEffectClient
with AIDL definitions.

In addition, this includes a small library that facilitates shared
memory regions over AIDL.

Bug: 160253486
Test: Ran effects-related CTS tests. Manual verification of basic
      audio functionality on Sargo.

Change-Id: I5a9c5f2f24c10072ad5067acc71aa30581af41c1
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 2e81ae7..ac41e82 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -349,7 +349,7 @@
 
                 sp<EffectHandle> createEffect_l(
                                     const sp<AudioFlinger::Client>& client,
-                                    const sp<IEffectClient>& effectClient,
+                                    const sp<media::IEffectClient>& effectClient,
                                     int32_t priority,
                                     audio_session_t sessionId,
                                     effect_descriptor_t *desc,