Rewrite psp1 libco

Major differences:

1. Use of SceUID casted to void* as cothread_t. This fixes semantics of
   co_active which now cann be called several times with results staying valid
   and removes bunch of malloc and free
2. In co_create immediately suspend new thread to avoid it running
   simultaneoulsy with creating thread

libco/psp1.c

@@ -4,42 +4,38 @@
 #include <stdlib.h>
 #include <pspthreadman.h>
 
-/* Since cothread_t is a void pointer it must contain an address. We can't return a reference to a local variable
- * because it would go out of scope, so we create a static variable instead so we can return a reference to it.
- */
-static SceUID active_thread_id = 0;
+typedef void (*entrypoint_t)(void);
 
 cothread_t co_active()
 {
-  active_thread_id = sceKernelGetThreadId();
-  return &active_thread_id;
+  return (void *) sceKernelGetThreadId();
+}
+
+static int thread_wrap(unsigned int argc, void *argp)
+{
+  entrypoint_t entrypoint = *(entrypoint_t *) argp;
+  sceKernelSleepThread();
+  entrypoint();
+  return 0;
 }
 
 cothread_t co_create(unsigned int size, void (*entrypoint)(void))
 {
-  /* Similar scenario as with active_thread_id except there will only be one active_thread_id while there could be many
-   * new threads each with their own handle, so we create them on the heap instead and delete them manually when they're
-   * no longer needed in co_delete().
-   */
-  cothread_t handle = malloc(sizeof(cothread_t));
-
-  /* SceKernelThreadEntry has a different signature than entrypoint, but in practice this seems to work */
-  SceUID new_thread_id = sceKernelCreateThread("cothread", (SceKernelThreadEntry)entrypoint, 0x12, size, 0, NULL);
-  sceKernelStartThread(new_thread_id, 0, NULL);
-
-  *(SceUID *)handle = new_thread_id;
-  return handle;
+  SceUID new_thread_id = sceKernelCreateThread("cothread", thread_wrap, 0x12, size, 0, NULL);
+  sceKernelStartThread(new_thread_id, sizeof (entrypoint), &entrypoint);
+  return (void *) new_thread_id;
 }
 
 void co_delete(cothread_t handle)
 {
-  sceKernelTerminateDeleteThread(*(SceUID *)handle);
-  free(handle);
+  SceUID id = (SceUID) handle;
+  sceKernelTerminateDeleteThread(id);
 }
 
 void co_switch(cothread_t handle)
 {
-  sceKernelWakeupThread(*(SceUID *)handle);
+  SceUID id = (SceUID) handle;
+  sceKernelWakeupThread(id);
   /* Sleep the currently active thread so the new thread can start */
   sceKernelSleepThread();
-}
+}