unix: fix epoll_event padding on riscv64

Change-Id: I88bccf0e671d350f8f57ac4d277adf4081054729
GitHub-Last-Rev: 330214261152f83f8ec4fdeaf95d1aab46b4b5fe
GitHub-Pull-Request: golang/sys#40
Reviewed-on: https://go-review.googlesource.com/c/sys/+/189877
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

unix/linux/types.go

@@ -276,7 +276,7 @@ struct my_epoll_event {
 	// padding is not specified in linux/eventpoll.h but added to conform to the
 	// alignment requirements of EABI
 	int32_t padFd;
-#elif defined(__powerpc64__) || defined(__s390x__) || defined(__sparc__)
+#elif defined(__powerpc64__) || defined(__s390x__) || defined(__sparc__) || defined(__riscv)
 	int32_t _padFd;
 #endif
 	int32_t fd;

unix/ztypes_linux_riscv64.go

@@ -808,6 +808,7 @@ type Ustat_t struct {
 
 type EpollEvent struct {
 	Events uint32
+	_      int32
 	Fd     int32
 	Pad    int32
 }