syscall: export X__ifi_pad and X_f on s390x and riscv64

This brings the exported field names on these GOARCHes
in line with the other supported linux platforms.

Fixes #57313.

Change-Id: I2107a7116ba60dc0c0a27f776318e3eb69e51682
Reviewed-on: https://go-review.googlesource.com/c/go/+/457557
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Bryan Mills <[email protected]>
Reviewed-by: Tobias Klauser <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Bryan Mills <[email protected]>

Author: Bryan C. Mills

src/syscall/mkpost.go

@@ -40,15 +40,21 @@ func main() {
 		re = regexp.MustCompile("Pad_cgo[A-Za-z0-9_]*")
 		s = re.ReplaceAllString(s, "_")
 
-		// We want to keep X__val in Fsid. Hide it and restore it later.
+		// We want to keep the X_ fields that are already consistently exported
+		// for the other linux GOARCH settings.
+		// Hide them and restore later.
 		s = strings.Replace(s, "X__val", "MKPOSTFSIDVAL", 1)
+		s = strings.Replace(s, "X__ifi_pad", "MKPOSTIFIPAD", 1)
+		s = strings.Replace(s, "X_f", "MKPOSTSYSINFOTF", 1)
 
 		// Replace other unwanted fields with blank identifiers.
 		re = regexp.MustCompile("X_[A-Za-z0-9_]*")
 		s = re.ReplaceAllString(s, "_")
 
-		// Restore X__val in Fsid.
+		// Restore preserved fields.
 		s = strings.Replace(s, "MKPOSTFSIDVAL", "X__val", 1)
+		s = strings.Replace(s, "MKPOSTIFIPAD", "X__ifi_pad", 1)
+		s = strings.Replace(s, "MKPOSTSYSINFOTF", "X_f", 1)
 
 		// Force the type of RawSockaddr.Data to [14]int8 to match
 		// the existing gccgo API.

src/syscall/ztypes_linux_riscv64.go

@@ -566,7 +566,7 @@ type Sysinfo_t struct {
 	Totalhigh uint64
 	Freehigh  uint64
 	Unit      uint32
-	_         [0]uint8
+	X_f       [0]uint8
 	_         [4]byte
 }
 

src/syscall/ztypes_linux_s390x.go

@@ -449,12 +449,12 @@ type RtAttr struct {
 }
 
 type IfInfomsg struct {
-	Family uint8
-	_      uint8
-	Type   uint16
-	Index  int32
-	Flags  uint32
-	Change uint32
+	Family     uint8
+	X__ifi_pad uint8
+	Type       uint16
+	Index      int32
+	Flags      uint32
+	Change     uint32
 }
 
 type IfAddrmsg struct {
@@ -564,7 +564,7 @@ type Sysinfo_t struct {
 	Totalhigh uint64
 	Freehigh  uint64
 	Unit      uint32
-	_         [0]uint8
+	X_f       [0]uint8
 	_         [4]byte
 }