Stop compiling some DSP-related files.

Replace it all with stubs.

src/dusk/audio/DspStub.cpp

@@ -0,0 +1,35 @@
+#include "JSystem/JAudio2/dspproc.h"
+#include "JSystem/JAudio2/osdsp_task.h"
+#include "JSystem/JAudio2/dsptask.h"
+#include "global.h"
+#include "os.h"
+
+void DSPReleaseHalt2(u32) {
+    CRASH("We do not directly emulate the DSP");
+}
+void DsetupTable(u32, u32, u32, u32, u32) {
+    // Nada.
+}
+void DsetMixerLevel(f32) {
+    // Nada for now, but maybe we should care about this?
+}
+void DsyncFrame2ch(u32, u32, u32) {
+    CRASH("We do not directly emulate the DSP");
+}
+void DsyncFrame4ch(u32, u32, u32, u32, u32) {
+    CRASH("We do not directly emulate the DSP");
+}
+
+void DspBoot(void (*)(void*)) {
+    CRASH("We do not directly emulate the DSP");
+}
+void DspFinishWork(u16) {
+    CRASH("We do not directly emulate the DSP");
+}
+int DSPSendCommands2(u32*, u32, void (*)(u16)) {
+    CRASH("We do not directly emulate the DSP");
+}
+
+void DsyncFrame2(u32, u32, u32) {
+    CRASH("We do not directly emulate the DSP");
+}