cmd/internal/obj: delete Rconv from LinkArch

It is unused and should have been deleted when Rconv was made
a global function.

Change-Id: Id745dcee6f0769604cabde04887c6d0c94855405
Reviewed-on: https://go-review.googlesource.com/6521Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/internal/obj/arm/obj5.go

@@ -1045,7 +1045,6 @@ var unaryDst = map[int]bool{
 }
 
 var Linkarm = obj.LinkArch{
-	Rconv:      Rconv,
 	ByteOrder:  binary.LittleEndian,
 	Pconv:      Pconv,
 	Name:       "arm",

src/cmd/internal/obj/i386/obj8.go

@@ -928,7 +928,6 @@ var unaryDst = map[int]bool{
 }
 
 var Link386 = obj.LinkArch{
-	Rconv:      Rconv,
 	ByteOrder:  binary.LittleEndian,
 	Pconv:      Pconv,
 	Name:       "386",

src/cmd/internal/obj/link.go

@@ -242,7 +242,6 @@ type Plist struct {
 
 type LinkArch struct {
 	Pconv      func(*Prog) string
-	Rconv      func(int) string
 	ByteOrder  binary.ByteOrder
 	Name       string
 	Thechar    int

src/cmd/internal/obj/ppc64/obj9.go

@@ -948,7 +948,6 @@ loop:
 }
 
 var Linkppc64 = obj.LinkArch{
-	Rconv:      Rconv,
 	ByteOrder:  binary.BigEndian,
 	Pconv:      Pconv,
 	Name:       "ppc64",
@@ -963,7 +962,6 @@ var Linkppc64 = obj.LinkArch{
 }
 
 var Linkppc64le = obj.LinkArch{
-	Rconv:      Rconv,
 	ByteOrder:  binary.LittleEndian,
 	Pconv:      Pconv,
 	Name:       "ppc64le",

src/cmd/internal/obj/x86/obj6.go

@@ -1134,7 +1134,6 @@ var unaryDst = map[int]bool{
 }
 
 var Linkamd64 = obj.LinkArch{
-	Rconv:      Rconv,
 	ByteOrder:  binary.LittleEndian,
 	Pconv:      Pconv,
 	Name:       "amd64",
@@ -1150,7 +1149,6 @@ var Linkamd64 = obj.LinkArch{
 }
 
 var Linkamd64p32 = obj.LinkArch{
-	Rconv:      Rconv,
 	ByteOrder:  binary.LittleEndian,
 	Pconv:      Pconv,
 	Name:       "amd64p32",