liblink: do not print pointers in debug output

Pointers change from run to run, making it hard to use
the debug output to identify the reason for a changed
object file.

Change-Id: I0c954da0943092c48686afc99ecf75eba516de6a
Reviewed-on: https://go-review.googlesource.com/3352Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Reviewed-by: Rob Pike <r@golang.org>

src/liblink/objfile.c

@@ -143,7 +143,7 @@ writeobj(Link *ctxt, Biobuf *b)
 	for(pl = ctxt->plist; pl != nil; pl = pl->link) {
 		for(p = pl->firstpc; p != nil; p = plink) {
 			if(ctxt->debugasm && ctxt->debugvlog)
-				print("obj: %p %P\n", p, p);
+				print("obj: %P\n", p);
 			plink = p->link;
 			p->link = nil;