go.sys: copy files from syscall package to go.sys/{plan9,windows,unix}

This CL copies to each package of go.sys the files from syscall it will need.
Different directories have different files, but these:
        mkall.sh
        str.go
        syscall.go
        mksyscall.pl
        race.go
        race0.go
        syscall_test.go
are copied to all three.
No changes yet, these are just copies. They are not ready to use yet:
package names are wrong, for starters. But this clean copy will make
it easier to follow the changes as the packages are enabled.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/126960043

unix/bpf_bsd.go

@@ -0,0 +1,169 @@
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+// Berkeley packet filter for BSD variants
+
+package syscall
+
+import (
+	"unsafe"
+)
+
+func BpfStmt(code, k int) *BpfInsn {
+	return &BpfInsn{Code: uint16(code), K: uint32(k)}
+}
+
+func BpfJump(code, k, jt, jf int) *BpfInsn {
+	return &BpfInsn{Code: uint16(code), Jt: uint8(jt), Jf: uint8(jf), K: uint32(k)}
+}
+
+func BpfBuflen(fd int) (int, error) {
+	var l int
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGBLEN, uintptr(unsafe.Pointer(&l)))
+	if err != 0 {
+		return 0, Errno(err)
+	}
+	return l, nil
+}
+
+func SetBpfBuflen(fd, l int) (int, error) {
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSBLEN, uintptr(unsafe.Pointer(&l)))
+	if err != 0 {
+		return 0, Errno(err)
+	}
+	return l, nil
+}
+
+func BpfDatalink(fd int) (int, error) {
+	var t int
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGDLT, uintptr(unsafe.Pointer(&t)))
+	if err != 0 {
+		return 0, Errno(err)
+	}
+	return t, nil
+}
+
+func SetBpfDatalink(fd, t int) (int, error) {
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSDLT, uintptr(unsafe.Pointer(&t)))
+	if err != 0 {
+		return 0, Errno(err)
+	}
+	return t, nil
+}
+
+func SetBpfPromisc(fd, m int) error {
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCPROMISC, uintptr(unsafe.Pointer(&m)))
+	if err != 0 {
+		return Errno(err)
+	}
+	return nil
+}
+
+func FlushBpf(fd int) error {
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCFLUSH, 0)
+	if err != 0 {
+		return Errno(err)
+	}
+	return nil
+}
+
+type ivalue struct {
+	name  [IFNAMSIZ]byte
+	value int16
+}
+
+func BpfInterface(fd int, name string) (string, error) {
+	var iv ivalue
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGETIF, uintptr(unsafe.Pointer(&iv)))
+	if err != 0 {
+		return "", Errno(err)
+	}
+	return name, nil
+}
+
+func SetBpfInterface(fd int, name string) error {
+	var iv ivalue
+	copy(iv.name[:], []byte(name))
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSETIF, uintptr(unsafe.Pointer(&iv)))
+	if err != 0 {
+		return Errno(err)
+	}
+	return nil
+}
+
+func BpfTimeout(fd int) (*Timeval, error) {
+	var tv Timeval
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGRTIMEOUT, uintptr(unsafe.Pointer(&tv)))
+	if err != 0 {
+		return nil, Errno(err)
+	}
+	return &tv, nil
+}
+
+func SetBpfTimeout(fd int, tv *Timeval) error {
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSRTIMEOUT, uintptr(unsafe.Pointer(tv)))
+	if err != 0 {
+		return Errno(err)
+	}
+	return nil
+}
+
+func BpfStats(fd int) (*BpfStat, error) {
+	var s BpfStat
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGSTATS, uintptr(unsafe.Pointer(&s)))
+	if err != 0 {
+		return nil, Errno(err)
+	}
+	return &s, nil
+}
+
+func SetBpfImmediate(fd, m int) error {
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCIMMEDIATE, uintptr(unsafe.Pointer(&m)))
+	if err != 0 {
+		return Errno(err)
+	}
+	return nil
+}
+
+func SetBpf(fd int, i []BpfInsn) error {
+	var p BpfProgram
+	p.Len = uint32(len(i))
+	p.Insns = (*BpfInsn)(unsafe.Pointer(&i[0]))
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSETF, uintptr(unsafe.Pointer(&p)))
+	if err != 0 {
+		return Errno(err)
+	}
+	return nil
+}
+
+func CheckBpfVersion(fd int) error {
+	var v BpfVersion
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCVERSION, uintptr(unsafe.Pointer(&v)))
+	if err != 0 {
+		return Errno(err)
+	}
+	if v.Major != BPF_MAJOR_VERSION || v.Minor != BPF_MINOR_VERSION {
+		return EINVAL
+	}
+	return nil
+}
+
+func BpfHeadercmpl(fd int) (int, error) {
+	var f int
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGHDRCMPLT, uintptr(unsafe.Pointer(&f)))
+	if err != 0 {
+		return 0, Errno(err)
+	}
+	return f, nil
+}
+
+func SetBpfHeadercmpl(fd, f int) error {
+	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSHDRCMPLT, uintptr(unsafe.Pointer(&f)))
+	if err != 0 {
+		return Errno(err)
+	}
+	return nil
+}