5c, 5g, 5l: fix arm bug

Using reg as the flag word was unfortunate, since the
default value is not 0 but NREG (==16), which happens
to be the bit NOPTR now.  Clear it.

If I say this will fix the build, it won't.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5690072

src/cmd/5c/txt.c

@@ -1185,7 +1185,8 @@ gpseudo(int a, Sym *s, Node *n)
 	if(a == ATEXT) {
 		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);

src/cmd/5g/gsubr.c

@@ -75,6 +75,7 @@ prog(int as)
 		p = dpc;
 		dpc = mal(sizeof(*dpc));
 		p->link = dpc;
+		p->reg = 0;  // used for flags
 	} else {
 		p = pc;
 		pc = mal(sizeof(*pc));
@@ -1116,7 +1117,8 @@ gins(int as, Node *f, Node *t)
 	if(f != N)
 		naddr(f, &af, 1);
 	if(t != N)
-		naddr(t, &at, 1);	p = prog(as);
+		naddr(t, &at, 1);
+	p = prog(as);
 	if(f != N)
 		p->from = af;
 	if(t != N)

src/cmd/5g/list.c

@@ -59,7 +59,7 @@ Pconv(Fmt *fp)
 	switch(p->as) {
 	default:
 		snprint(str1, sizeof(str1), "%A%C", p->as, p->scond);
-		if(p->reg == NREG)
+		if(p->reg == NREG && p->as != AGLOBL)
 			snprint(str, sizeof(str), "%.4d (%L) %-7s	%D,%D", 
 				p->loc, p->lineno, str1, &p->from, &p->to);
 		else

src/cmd/5l/list.c

@@ -65,7 +65,7 @@ Pconv(Fmt *fp)
 	switch(a) {
 	default:
 		fmtprint(fp, "(%d)", p->line);
-		if(p->reg == NREG)
+		if(p->reg == NREG && p->as != AGLOBL)
 			fmtprint(fp, "	%A%C	%D,%D",
 				a, p->scond, &p->from, &p->to);
 		else