sceIo: host0: behaves like usbhostfs with dispatch suspended

With dispatch suspended, IO fails in the driver when it tries to wait. The
memory stick driver returns SCE_KERNEL_ERROR_CAN_NOT_WAIT, while usbhostfs,
which serves host0: under PSPLink, returns -1. host0: is mostly what
homebrew developers run from, so it now does the same.

Also from threads/scheduling/dispatch, which now passes:
- sceIoRead reports an async operation still in progress before failing
  on suspended dispatch.
- A write to stdout or stderr doesn't give up the CPU.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

test.py

@@ -388,6 +388,7 @@ tests_good = [
   "threads/mutex/try",
   "threads/mutex/unlock",
   "threads/mutex/unlock2",
+  "threads/scheduling/dispatch",
   "threads/semaphores/semaphores",
   "threads/semaphores/cancel",
   "threads/semaphores/create",
@@ -598,7 +599,6 @@ tests_next = [
   # These two mbx tests only appeared to work because they papered over bugs 
 
 
-  "threads/scheduling/dispatch",
   "threads/scheduling/scheduling",
   "threads/threads/create",
   "threads/tls/memory",