lib9: remove unreferenced externs and getuser()

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6820115

include/libc.h

@@ -85,16 +85,12 @@ extern	char*	p9getenv(char*);
 extern	int	p9putenv(char*, char*);
 extern	int	getfields(char*, char**, int, int, char*);
 extern	int	gettokens(char *, char **, int, char *);
-extern	char*	getuser(void);
 extern	char*	p9getwd(char*, int);
 extern	void	p9longjmp(p9jmp_buf, int);
-extern	char*	mktemp(char*);
-extern	int		opentemp(char*);
 extern	void	p9notejmp(void*, p9jmp_buf, int);
 extern	void	perror(const char*);
 extern	int	postnote(int, int, char *);
 extern	double	p9pow10(int);
-extern	char*	searchpath(char*);
 extern	char*	p9ctime(long);
 #define p9setjmp(b)	sigsetjmp((void*)(b), 1)
 

src/lib9/getuser.c

-// +build !windows
-
-/*
-Plan 9 from User Space src/lib9/getuser.c
-http://code.swtch.com/plan9port/src/tip/src/lib9/getuser.c
-
-Copyright 2001-2007 Russ Cox.  All Rights Reserved.
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in
-all copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-THE SOFTWARE.
-*/
-
-#include <u.h>
-#include <pwd.h>
-#include <libc.h>
-
-char*
-getuser(void)
-{
-	static char user[64];
-	struct passwd *pw;
-
-	pw = getpwuid(getuid());
-	if(pw == nil)
-		return "none";
-	strecpy(user, user+sizeof user, pw->pw_name);
-	return user;
-}