cmd: fix format strings used with obj.Headtype

Found by vet. Introduced by CL 28853.

Change-Id: I3199e0cbdb1c512ba29eb7e4d5c1c98963f5a954
Reviewed-on: https://go-review.googlesource.com/28957
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/internal/obj/x86/asm6.go

@@ -2188,7 +2188,7 @@ func prefixof(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) int {
 					if isAndroid {
 						return 0x65 // GS
 					}
-					log.Fatalf("unknown TLS base register for %s", ctxt.Headtype)
+					log.Fatalf("unknown TLS base register for %v", ctxt.Headtype)
 
 				case obj.Hdarwin,
 					obj.Hdragonfly,
@@ -2201,7 +2201,7 @@ func prefixof(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) int {
 
 			switch ctxt.Headtype {
 			default:
-				log.Fatalf("unknown TLS base register for %s", ctxt.Headtype)
+				log.Fatalf("unknown TLS base register for %v", ctxt.Headtype)
 
 			case obj.Hlinux:
 				if isAndroid {
@@ -4016,7 +4016,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
 						// are handled in prefixof above and should not be listed here.
 						switch ctxt.Headtype {
 						default:
-							log.Fatalf("unknown TLS base location for %s", ctxt.Headtype)
+							log.Fatalf("unknown TLS base location for %v", ctxt.Headtype)
 
 						case obj.Hlinux,
 							obj.Hnacl:
@@ -4092,7 +4092,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
 
 					switch ctxt.Headtype {
 					default:
-						log.Fatalf("unknown TLS base location for %s", ctxt.Headtype)
+						log.Fatalf("unknown TLS base location for %v", ctxt.Headtype)
 
 					case obj.Hlinux:
 						if !ctxt.Flag_shared {

src/cmd/link/internal/amd64/obj.go

@@ -99,7 +99,7 @@ func archinit(ctxt *ld.Link) {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
+			log.Fatalf("cannot use -linkmode=external with -H %v", ld.Headtype)
 		}
 
 	case obj.Hdarwin,

src/cmd/link/internal/arm/obj.go

@@ -95,7 +95,7 @@ func archinit(ctxt *ld.Link) {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
+			log.Fatalf("cannot use -linkmode=external with -H %v", ld.Headtype)
 		}
 
 	case obj.Hlinux,

src/cmd/link/internal/arm64/obj.go

@@ -97,7 +97,7 @@ func archinit(ctxt *ld.Link) {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
+			log.Fatalf("cannot use -linkmode=external with -H %v", ld.Headtype)
 		}
 	case obj.Hlinux, obj.Hdarwin:
 		break

src/cmd/link/internal/ld/data.go

@@ -429,7 +429,7 @@ func relocsym(ctxt *Link, s *Symbol) {
 			} else if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 				o = r.Add
 			} else {
-				log.Fatalf("unexpected R_TLS_LE relocation for %s", Headtype)
+				log.Fatalf("unexpected R_TLS_LE relocation for %v", Headtype)
 			}
 
 		case obj.R_TLS_IE:

src/cmd/link/internal/ld/sym.go

@@ -60,7 +60,7 @@ func linknew(arch *sys.Arch) *Link {
 func (ctxt *Link) computeTLSOffset() {
 	switch Headtype {
 	default:
-		log.Fatalf("unknown thread-local storage offset for %s", Headtype)
+		log.Fatalf("unknown thread-local storage offset for %v", Headtype)
 
 	case obj.Hplan9, obj.Hwindows, obj.Hwindowsgui:
 		break

src/cmd/link/internal/mips64/obj.go

@@ -105,7 +105,7 @@ func archinit(ctxt *ld.Link) {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
+			log.Fatalf("cannot use -linkmode=external with -H %v", ld.Headtype)
 		}
 
 	case obj.Hlinux:

src/cmd/link/internal/ppc64/obj.go

@@ -120,7 +120,7 @@ func archinit(ctxt *ld.Link) {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
+			log.Fatalf("cannot use -linkmode=external with -H %v", ld.Headtype)
 		}
 
 	case obj.Hlinux:

src/cmd/link/internal/x86/obj.go

@@ -98,7 +98,7 @@ func archinit(ctxt *ld.Link) {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
+			log.Fatalf("cannot use -linkmode=external with -H %v", ld.Headtype)
 		}
 
 	case obj.Hdarwin,