8l: remove left over debugging

        This line was triggering a null dereference warning
        under clang-3.0. The line was added in a46819aa9150
        but compared to it's sibling in 6l it appears to be
        leftover debugging.

R=rsc
CC=golang-dev
https://golang.org/cl/5049042

src/cmd/8l/asm.c

@@ -417,7 +417,7 @@ adddynsym(Sym *s)
 		return;
 	
 	if(s->dynimpname == nil)
-		diag("adddynsym: no dynamic name for %s", s->name, *(int32*)0);
+		diag("adddynsym: no dynamic name for %s", s->name);
 
 	if(iself) {
 		s->dynid = nelfsym++;