- remove unused variables
- let the system pick the segattach address, to allow for systems
such as amd64 or the raspberry pi which may have more heap,
or less address space than the guess address, respectively.

Reference: /n/sources/patch/applied/_buf-upd
Date: Tue Apr 30 04:12:13 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/ape/lib/ap/plan9/_buf.c	Tue Apr 30 04:10:18 2013
+++ /sys/src/ape/lib/ap/plan9/_buf.c	Tue Apr 30 04:10:11 2013
@@ -23,7 +23,6 @@
 	Muxbuf	bufs[INITBUFS];		/* can grow, via segbrk() */
 } Muxseg;
 
-#define MUXADDR ((void*)0x6000000)
 static Muxseg *mux = 0;			/* shared memory segment */
 
 /* _muxsid and _killmuxsid are known in libbsd's listen.c */
@@ -50,15 +49,15 @@
 int
 _startbuf(int fd)
 {
-	long i, n, slot;
-	int pid, sid;
+	long i, slot;
+	int pid;
 	Fdinfo *f;
 	Muxbuf *b;
 
 	if(mux == 0){
 		_RFORK(RFREND);
-		mux = (Muxseg*)_SEGATTACH(0, "shared", MUXADDR, sizeof(Muxseg));
-		if((long)mux == -1){
+		mux = (Muxseg*)_SEGATTACH(0, "shared", 0, sizeof(Muxseg));
+		if(mux == (void*)-1){
 			_syserrno();
 			return -1;
 		}
@@ -264,7 +263,7 @@
 int
 select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeval *timeout)
 {
-	int n, i, tmp, t, slots, fd, err;
+	int n, i, t, slots, fd, err;
 	Fdinfo *f;
 	Muxbuf *b;
 
@@ -368,7 +367,7 @@
 static int timerpid;
 
 static void
-alarmed(int v)
+alarmed(int)
 {
 	timerreset = 1;
 }
@@ -454,11 +453,8 @@
 }
 
 static int
-copynotehandler(void *u, char *msg)
+copynotehandler(void*, char*)
 {
-	int i;
-	void(*f)(int);
-
 	if(_finishing)
 		_finish(0, 0);
 	_NOTED(1);