runtime: mark traceEnabled as no:split

The traceEnabled function splits the stack and is being
called by reentersyscall that shouldn't call anything
that splits the stack. Same with traceShuttingDown.

Fixes #61975

Author: mauri870

src/runtime/trace.go

@@ -257,11 +257,15 @@ func traceBufPtrOf(b *traceBuf) traceBufPtr {
 }
 
 // traceEnabled returns true if the trace is currently enabled.
+//
+//go:nosplit
 func traceEnabled() bool {
 	return trace.enabled
 }
 
 // traceShuttingDown returns true if the trace is currently shutting down.
+//
+//go:nosplit
 func traceShuttingDown() bool {
 	return trace.shutdown
 }