Vendor Teakra, make emulator own DSP RAM and add DSP RAM to fastmem (#806)

* DSP: Own DSP RAM and add it to fastmem

* Vendor Teakra

* Add MacOS support to fastmem

* Fix MacOS fastmem paths

* Fix iOS build

third_party/teakra/src/shared_memory.h

@@ -0,0 +1,35 @@
+#pragma once
+#include <array>
+#include <memory>
+#include <optional>
+#include "common_types.h"
+
+namespace Teakra {
+struct SharedMemory {
+    // We allocate our own memory if the user doesn't supply their own
+    std::unique_ptr<std::array<u8, 0x80000>> own_memory;
+    // Points to either own own memory or user-supplied memory
+    u8* raw;
+
+    SharedMemory(u8* mem = nullptr) : raw{mem} {
+        if (mem == nullptr) {
+            own_memory = std::make_unique<std::array<u8, 0x80000>>();
+            raw = own_memory->data();
+        }
+    }
+
+    u16 ReadWord(u32 word_address) const {
+        u32 byte_address = word_address * 2;
+        u8 low = raw[byte_address];
+        u8 high = raw[byte_address + 1];
+        return low | ((u16)high << 8);
+    }
+    void WriteWord(u32 word_address, u16 value) {
+        u8 low = value & 0xFF;
+        u8 high = value >> 8;
+        u32 byte_address = word_address * 2;
+        raw[byte_address] = low;
+        raw[byte_address + 1] = high;
+    }
+};
+} // namespace Teakra