merge branch 'pr-1613'

libcontainer: merge common syscall implementations

LGTMs: @crosbymichael @cyphar
Closes #1613

libcontainer/system/syscall_linux_32.go

@@ -1,4 +1,5 @@
-// +build linux,386
+// +build linux
+// +build 386 arm
 
 package system
 

libcontainer/system/syscall_linux_64.go

@@ -1,4 +1,5 @@
-// +build linux,arm64 linux,amd64 linux,ppc linux,ppc64 linux,ppc64le linux,s390x
+// +build linux
+// +build arm64 amd64 mips mipsle mips64 mips64le ppc ppc64 ppc64le s390x
 
 package system
 

libcontainer/system/syscall_linux_arm.go

@@ -1,25 +0,0 @@
-// +build linux,arm
-
-package system
-
-import (
-	"golang.org/x/sys/unix"
-)
-
-// Setuid sets the uid of the calling thread to the specified uid.
-func Setuid(uid int) (err error) {
-	_, _, e1 := unix.RawSyscall(unix.SYS_SETUID32, uintptr(uid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}
-
-// Setgid sets the gid of the calling thread to the specified gid.
-func Setgid(gid int) (err error) {
-	_, _, e1 := unix.RawSyscall(unix.SYS_SETGID32, uintptr(gid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}

libcontainer/system/syscall_linux_mipsx.go

@@ -1,25 +0,0 @@
-// +build linux,mips linux,mipsle linux,mips64 linux,mips64le
-
-package system
-
-import (
-	"syscall"
-)
-
-// Setuid sets the uid of the calling thread to the specified uid.
-func Setuid(uid int) (err error) {
-	_, _, e1 := syscall.RawSyscall(syscall.SYS_SETUID, uintptr(uid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}
-
-// Setgid sets the gid of the calling thread to the specified gid.
-func Setgid(gid int) (err error) {
-	_, _, e1 := syscall.RawSyscall(syscall.SYS_SETGID, uintptr(gid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}