patch in proper branch address in zaddr output

R=rsc
APPROVED=rsc
DELTA=12  (11 added, 1 deleted, 0 changed)
OCL=34658
CL=34664

src/cmd/5g/gobj.c

@@ -120,7 +120,6 @@ zaddr(Biobuf *b, Addr *a, int s)
 		Bputc(b, l>>24); // fall through
 	case D_OREG:
 	case D_CONST:
-	case D_BRANCH:
 	case D_SHIFT:
 	case D_STATIC:
 	case D_AUTO:
@@ -133,6 +132,17 @@ zaddr(Biobuf *b, Addr *a, int s)
 		Bputc(b, l>>24);
 		break;
 
+	case D_BRANCH:
+		if(a->branch == nil)
+			fatal("unpatched branch");
+		a->offset = a->branch->loc;
+		l = a->offset;
+		Bputc(b, l);
+		Bputc(b, l>>8);
+		Bputc(b, l>>16);
+		Bputc(b, l>>24);
+		break;
+
 	case D_SCONST:
 		n = a->sval;
 		for(i=0; i<NSNAME; i++) {