syscall: use 64-bit file size for truncation on Linux

Truncate and Ftruncate for 32-bit Linux should use 64-bit
offset system calls.

R=rsc
CC=golang-dev, royger
https://golang.org/cl/2943041
diff --git a/src/pkg/syscall/zsyscall_linux_amd64.go b/src/pkg/syscall/zsyscall_linux_amd64.go
index d851d1e..e08525b 100644
--- a/src/pkg/syscall/zsyscall_linux_amd64.go
+++ b/src/pkg/syscall/zsyscall_linux_amd64.go
@@ -273,14 +273,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Ftruncate(fd int, length int64) (errno int) {
-	_, _, e1 := Syscall(SYS_FTRUNCATE, uintptr(fd), uintptr(length), 0)
-	errno = int(e1)
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Getdents(fd int, buf []byte) (n int, errno int) {
 	var _p0 unsafe.Pointer
 	if len(buf) > 0 {
@@ -645,14 +637,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Truncate(path string, length int64) (errno int) {
-	_, _, e1 := Syscall(SYS_TRUNCATE, uintptr(unsafe.Pointer(StringBytePtr(path))), uintptr(length), 0)
-	errno = int(e1)
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Umask(mask int) (oldmask int) {
 	r0, _, _ := Syscall(SYS_UMASK, uintptr(mask), 0, 0)
 	oldmask = int(r0)
@@ -780,6 +764,14 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Ftruncate(fd int, length int64) (errno int) {
+	_, _, e1 := Syscall(SYS_FTRUNCATE, uintptr(fd), uintptr(length), 0)
+	errno = int(e1)
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getegid() (egid int) {
 	r0, _, _ := Syscall(SYS_GETEGID, 0, 0, 0)
 	egid = int(r0)
@@ -984,6 +976,14 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Truncate(path string, length int64) (errno int) {
+	_, _, e1 := Syscall(SYS_TRUNCATE, uintptr(unsafe.Pointer(StringBytePtr(path))), uintptr(length), 0)
+	errno = int(e1)
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func accept(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (fd int, errno int) {
 	r0, _, e1 := Syscall(SYS_ACCEPT, uintptr(s), uintptr(unsafe.Pointer(rsa)), uintptr(unsafe.Pointer(addrlen)))
 	fd = int(r0)