keep line number history even when

throwing away dead code at end of file.

also fix an uninitialized memory error
found by valgrind.

R=r
DELTA=7  (5 added, 2 deleted, 0 changed)
OCL=23991
CL=23994

src/cmd/6l/obj.c

@@ -757,6 +757,7 @@ addhist(int32 line, int type)
 	u->link = curhist;
 	curhist = u;
 
+	s->name[0] = 0;
 	j = 1;
 	for(i=0; i<histfrogp; i++) {
 		k = histfrog[i]->value;
@@ -764,6 +765,8 @@ addhist(int32 line, int type)
 		s->name[j+1] = k;
 		j += 2;
 	}
+	s->name[j] = 0;
+	s->name[j+1] = 0;
 }
 
 void

src/cmd/6l/span.c

@@ -240,8 +240,6 @@ asmsym(void)
 
 	for(p=textp; p!=P; p=p->pcond) {
 		s = p->from.sym;
-		if(s->type != STEXT)
-			continue;
 
 		/* filenames first */
 		for(a=p->to.autom; a; a=a->link)
@@ -251,6 +249,8 @@ asmsym(void)
 			if(a->type == D_FILE1)
 				putsymb(a->asym->name, 'Z', a->aoffset, 0, nil);
 
+		if(s->type != STEXT)
+			continue;
 		putsymb(s->name, 'T', s->value, s->version, gotypefor(s->name));
 
 		/* frame, auto and param after */