runtime: disable event scanning error reporting on solaris

It seems like we need to pay special attention to capturing error
condition on the event port of SmartOS. The previous attempt CL 167777
works on Oracle Solaris but doesn't work on SmartOS for the uncertain
reason. It's better to disable the reporting for now.

Updates #30624.
Fixes #30840.

Change-Id: Ieca5dac4fceb7e8c9cb4db149bb4c2e79691588c
Reviewed-on: https://go-review.googlesource.com/c/go/+/167782
Run-TryBot: Mikio Hara <mikioh.public.networking@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/netpoll_solaris.go

@@ -233,10 +233,11 @@ retry:
 		}
 
 		if mode != 0 {
-			pd.everr = false
-			if ev.portev_events == _POLLERR {
-				pd.everr = true
-			}
+			// TODO(mikio): Consider implementing event
+			// scanning error reporting once we are sure
+			// about the event port on SmartOS.
+			//
+			// See golang.org/x/issue/30840.
 			netpollready(&toRun, pd, mode)
 		}
 	}