runtime: add support for panic/recover in Plan 9 note handler
This change also resolves some issues with note handling: we now make
sure that there is enough room at the bottom of every goroutine to
execute the note handler, and the `exitstatus' is no longer a global
entity, which resolves some race conditions.
R=rminnich, npe, rsc, ality
CC=golang-dev
https://golang.org/cl/6569068
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 22aead7..187a827 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -296,6 +296,9 @@
#ifdef GOOS_windows
void* thread; // thread handle
#endif
+#ifdef GOOS_plan9
+ int8* notesig;
+#endif
SEH* seh;
uintptr end[];
};
