Change syscall.EPOLLET to unix.EPOLLET

syscall.EPOLLET has been defined with different values on amd64 and
arm64(-0x80000000 on amd64, and 0x80000000 on arm64), while unix.EPOLLET
has been unified this value to 0x80000000(golang/go#5328). ref #63

Signed-off-by: Haibo Xu <haibo.xu@arm.com>
Change-Id: Id97d075c4e79d86a2ea3227ffbef02d8b00ffbb8

pkg/fdnotifier/BUILD

@@ -10,5 +10,8 @@ go_library(
     ],
     importpath = "gvisor.dev/gvisor/pkg/fdnotifier",
     visibility = ["//:sandbox"],
-    deps = ["//pkg/waiter"],
+    deps = [
+        "//pkg/waiter",
+        "@org_golang_x_sys//unix:go_default_library",
+    ],
 )

pkg/fdnotifier/fdnotifier.go

@@ -25,6 +25,7 @@ import (
 	"sync"
 	"syscall"
 
+	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
@@ -72,7 +73,7 @@ func (n *notifier) waitFD(fd int32, fi *fdInfo, mask waiter.EventMask) error {
 	}
 
 	e := syscall.EpollEvent{
-		Events: mask.ToLinux() | -syscall.EPOLLET,
+		Events: mask.ToLinux() | unix.EPOLLET,
 		Fd:     fd,
 	}
 

pkg/sentry/socket/rpcinet/notifier/BUILD

@@ -11,5 +11,6 @@ go_library(
         "//pkg/sentry/socket/rpcinet:syscall_rpc_go_proto",
         "//pkg/sentry/socket/rpcinet/conn",
         "//pkg/waiter",
+        "@org_golang_x_sys//unix:go_default_library",
     ],
 )

pkg/sentry/socket/rpcinet/notifier/notifier.go

@@ -20,6 +20,7 @@ import (
 	"sync"
 	"syscall"
 
+	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/sentry/socket/rpcinet/conn"
 	pb "gvisor.dev/gvisor/pkg/sentry/socket/rpcinet/syscall_rpc_go_proto"
 	"gvisor.dev/gvisor/pkg/waiter"
@@ -76,7 +77,7 @@ func (n *Notifier) waitFD(fd uint32, fi *fdInfo, mask waiter.EventMask) error {
 	}
 
 	e := pb.EpollEvent{
-		Events: mask.ToLinux() | -syscall.EPOLLET,
+		Events: mask.ToLinux() | unix.EPOLLET,
 		Fd:     fd,
 	}