lib9: enable on Plan 9

This change depends on CL 57170052.

LGTM=rsc
R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/60840049

include/plan9/errno.h

@@ -0,0 +1,7 @@
+// Copyright 2014 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.
+
+int errno;
+
+#define ERANGE 1001

include/plan9/fmt.h

@@ -0,0 +1,64 @@
+// Copyright 2014 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.
+
+#include "../fmt.h"
+
+#pragma	varargck	argpos	fmtprint	2
+#pragma	varargck	argpos	fprint		2
+#pragma	varargck	argpos	print		1
+#pragma	varargck	argpos	runeseprint	3
+#pragma	varargck	argpos	runesmprint	1
+#pragma	varargck	argpos	runesnprint	3
+#pragma	varargck	argpos	runesprint	2
+#pragma	varargck	argpos	seprint		3
+#pragma	varargck	argpos	smprint		1
+#pragma	varargck	argpos	snprint		3
+#pragma	varargck	argpos	sprint		2
+
+#pragma	varargck	type	"lld"	vlong
+#pragma	varargck	type	"llo"	vlong
+#pragma	varargck	type	"llx"	vlong
+#pragma	varargck	type	"llb"	vlong
+#pragma	varargck	type	"lld"	uvlong
+#pragma	varargck	type	"llo"	uvlong
+#pragma	varargck	type	"llx"	uvlong
+#pragma	varargck	type	"llb"	uvlong
+#pragma	varargck	type	"ld"	long
+#pragma	varargck	type	"lo"	long
+#pragma	varargck	type	"lx"	long
+#pragma	varargck	type	"lb"	long
+#pragma	varargck	type	"ld"	ulong
+#pragma	varargck	type	"lo"	ulong
+#pragma	varargck	type	"lx"	ulong
+#pragma	varargck	type	"lb"	ulong
+#pragma	varargck	type	"d"	int
+#pragma	varargck	type	"o"	int
+#pragma	varargck	type	"x"	int
+#pragma	varargck	type	"c"	int
+#pragma	varargck	type	"C"	int
+#pragma	varargck	type	"b"	int
+#pragma	varargck	type	"d"	uint
+#pragma	varargck	type	"x"	uint
+#pragma	varargck	type	"c"	uint
+#pragma	varargck	type	"C"	uint
+#pragma	varargck	type	"b"	uint
+#pragma	varargck	type	"f"	double
+#pragma	varargck	type	"e"	double
+#pragma	varargck	type	"g"	double
+#pragma	varargck	type	"s"	char*
+#pragma	varargck	type	"q"	char*
+#pragma	varargck	type	"S"	Rune*
+#pragma	varargck	type	"Q"	Rune*
+#pragma	varargck	type	"r"	void
+#pragma	varargck	type	"%"	void
+#pragma	varargck	type	"n"	int*
+#pragma	varargck	type	"p"	uintptr
+#pragma	varargck	type	"p"	void*
+#pragma	varargck	flag	','
+#pragma	varargck	flag	' '
+#pragma	varargck	flag	'h'
+#pragma	varargck	type	"<"	void*
+#pragma	varargck	type	"["	void*
+#pragma	varargck	type	"H"	void*
+#pragma	varargck	type	"lH"	void*

include/plan9/libc.h

@@ -2,8 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "/sys/include/libc.h"
 #include "/sys/include/ctype.h"
+#include "fmt.h"
+#include "utf.h"
+#include "libc_plan9.h"
 
 char*	getgoos(void);
 char*	getgoarch(void);
@@ -26,3 +28,6 @@ void	flagprint(int);
 // The libraries use size_t to avoid -Wconversion warnings from GCC
 // when calling standard library functions like memcpy.
 typedef unsigned long size_t;
+
+// math.h
+#define HUGE_VAL 1.79769313486231e+308

include/plan9/mklibc.rc

@@ -0,0 +1,13 @@
+#!/bin/rc
+
+pattern='/umuldiv/d
+	/UTFmax/d
+	/Runesync/d
+	/Runeself/d
+	/Runeerror/d
+	/Runemax/d
+	/rune routines/,/^\/\*/d
+	/print routines/,/^\/\*/d
+	/error string for/,/^\/\*/d'
+
+sed -e $pattern /sys/include/libc.h

include/plan9/stdarg.h

@@ -0,0 +1,3 @@
+// Copyright 2014 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.

include/plan9/utf.h

@@ -0,0 +1,5 @@
+// Copyright 2014 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.
+
+#include "../utf.h"