AudioCore: Skeleton Implementation

This commit:
* Adds a new subproject, audio_core.
* Defines structures that exist in DSP shared memory.
* Hooks up various other parts of the emulator into audio core.

This sets the foundation for a later HLE DSP implementation.

src/audio_core/audio_core.h

@@ -0,0 +1,26 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+namespace Kernel {
+class VMManager;
+}
+
+namespace AudioCore {
+
+constexpr int num_sources = 24;
+constexpr int samples_per_frame = 160;     ///< Samples per audio frame at native sample rate
+constexpr int native_sample_rate = 32728;  ///< 32kHz
+
+/// Initialise Audio Core
+void Init();
+
+/// Add DSP address spaces to a Process.
+void AddAddressSpace(Kernel::VMManager& vm_manager);
+
+/// Shutdown Audio Core
+void Shutdown();
+
+} // namespace