libgo: update to Go 1.8 release candidate 1

Compiler changes:
      * Change map assignment to use mapassign and assign value directly.
      * Change string iteration to use decoderune, faster for ASCII strings.
      * Change makeslice to take int, and use makeslice64 for larger values.
      * Add new noverflow field to hmap struct used for maps.
    
    Unresolved problems, to be fixed later:
      * Commented out test in go/types/sizes_test.go that doesn't compile.
      * Commented out reflect.TestStructOf test for padding after zero-sized field.
    
    Reviewed-on: https://go-review.googlesource.com/35231

gotools/:
	Updates for Go 1.8rc1.
	* Makefile.am (go_cmd_go_files): Add bug.go.
	(s-zdefaultcc): Write defaultPkgConfig.
	* Makefile.in: Rebuild.

From-SVN: r244456

libgo/go/golang_org/x/net/lif/syscall.go

@@ -0,0 +1,33 @@
+// Copyright 2016 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 solaris
+
+package lif
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+//go:cgo_import_dynamic libc_ioctl ioctl "libc.so"
+
+//go:linkname procIoctl libc_ioctl
+
+var procIoctl uintptr
+
+func sysvicall6(trap, nargs, a1, a2, a3, a4, a5, a6 uintptr) (uintptr, uintptr, syscall.Errno)
+
+// TODO: replace with runtime.KeepAlive when available
+//go:noescape
+func keepAlive(p unsafe.Pointer)
+
+func ioctl(s, ioc uintptr, arg unsafe.Pointer) error {
+	_, _, errno := sysvicall6(uintptr(unsafe.Pointer(&procIoctl)), 3, s, ioc, uintptr(arg), 0, 0, 0)
+	keepAlive(arg)
+	if errno != 0 {
+		return error(errno)
+	}
+	return nil
+}