port: revert multithreaded audio experiments

until I can figure out how to fix all the funny concurrency issues that cropped up

port/include/audio.h

@@ -6,6 +6,7 @@
 s32 audioInit(void);
 s32 audioGetBytesBuffered(void);
 s32 audioGetSamplesBuffered(void);
-void audioSubmitBuffer(const s16 *buf, u32 size);
+void audioSetNextBuffer(const s16 *buf, u32 len);
+void audioEndFrame(void);
 
 #endif

port/include/system.h

@@ -35,11 +35,7 @@ void *sysMemZeroAlloc(const u32 size);
 void sysMemFree(void *ptr);
 
 // hns is specified in 100ns units
-// do not use sysFrameLimiterSleep on any thread other than the main one
-void sysFrameLimiterSleep(const s64 hns);
-
-// us is specified in microseconds
-void sysSleep(const s64 us);
+void sysSleep(const s64 hns);
 
 // yield CPU if supported (e.g. during a busy loop)
 void sysCpuRelax(void);

port/include/thread.h

@@ -1,27 +0,0 @@
-#ifndef _IN_THREAD_H
-#define _IN_THREAD_H
-
-#include <PR/ultratypes.h>
-#include "platform.h"
-
-// TODO: backends
-#ifndef PLATFORM_USE_PTHREAD
-#error "No available thread backend."
-#endif
-
-#include <pthread.h>
-
-#define SYSMUTEX_STATIC_INIT PTHREAD_MUTEX_INITIALIZER
-
-typedef pthread_t systhread;
-typedef pthread_mutex_t sysmutex;
-
-typedef void *(*systhreadfn)(void *);
-
-s32 sysThreadCreate(systhread *thread, systhreadfn func, void *arg);
-s32 sysThreadJoin(systhread *thread, void **result);
-
-void sysMutexLock(sysmutex *mtx);
-void sysMutexUnlock(sysmutex *mtx);
-
-#endif // _IN_THREAD_H