cmd/ld, cmd/8l: Fix OpenBSD build.

Don't generate TLS sections on OpenBSD.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8059043

src/cmd/8l/span.c

@@ -689,7 +689,7 @@ putrelv:
 		r = addrel(cursym);
 		*r = rel;
 		r->off = curp->pc + andptr - and;
-	} else if(iself && linkmode == LinkExternal && istls(a)) {
+	} else if(iself && linkmode == LinkExternal && istls(a) && HEADTYPE != Hopenbsd) {
 		Reloc *r;
 		Sym *s;
 

src/cmd/ld/data.c

@@ -1206,7 +1206,7 @@ dodata(void)
 	sect->len = datsize - sect->vaddr;
 	lookup("end", 0)->sect = sect;
 	
-	if(iself && linkmode == LinkExternal && s != nil && s->type == STLSBSS) {
+	if(iself && linkmode == LinkExternal && s != nil && s->type == STLSBSS && HEADTYPE != Hopenbsd) {
 		sect = addsection(&segdata, ".tbss", 06);
 		sect->align = PtrSize;
 		sect->vaddr = 0;

src/cmd/ld/elf.c

@@ -887,7 +887,7 @@ doelf(void)
 	addstring(shstrtab, ".data");
 	addstring(shstrtab, ".bss");
 	addstring(shstrtab, ".noptrbss");
-	if(linkmode == LinkExternal)
+	if(linkmode == LinkExternal && HEADTYPE != Hopenbsd)
 		addstring(shstrtab, ".tbss");
 	if(HEADTYPE == Hnetbsd)
 		addstring(shstrtab, ".note.netbsd.ident");