cmd/5c: fix dataflag annotation

file        old_size     new_size    base@c1ce95068533
bin/go      14717392     6287824     5918236

this huge size difference is due to GC data for runtime.mheap
(NOPTR dataflag is not obeyed).

R=rsc, dave
CC=golang-dev
https://golang.org/cl/6547051

src/cmd/5c/txt.c

@@ -1176,17 +1176,15 @@ patch(Prog *op, int32 pc)
 void
 gpseudo(int a, Sym *s, Node *n)
 {
-
 	nextpc();
 	p->as = a;
 	p->from.type = D_OREG;
 	p->from.sym = s;
 	p->from.name = D_EXTERN;
-	if(a == ATEXT) {
+	if(a == ATEXT || a == AGLOBL) {
 		p->reg = textflag;
 		textflag = 0;
-	} else if(a == AGLOBL)
-		p->reg = 0;
+	}
 	if(s->class == CSTATIC)
 		p->from.name = D_STATIC;
 	naddr(n, &p->to);