cmd/link: remove support for windows/arm relocations

The windows/arm port is no longer supported. We can remove the
related code from cmd/link/internal/arm.

For golang#71671

Change-Id: I00de1231482cc2f28ec5fc9dc62e81f0ba3fe481
Reviewed-on: https://go-review.googlesource.com/c/go/+/703778
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
Reviewed-by: Than McIntosh <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>

Author: qmuntal

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

@@ -334,36 +334,7 @@ func machoreloc1(*sys.Arch, *ld.OutBuf, *loader.Loader, loader.Sym, loader.ExtRe
 }
 
 func pereloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
-	rs := r.Xsym
-	rt := r.Type
-
-	if ldr.SymDynid(rs) < 0 {
-		ldr.Errorf(s, "reloc %d (%s) to non-coff symbol %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymType(rs), ldr.SymType(rs))
-		return false
-	}
-
-	out.Write32(uint32(sectoff))
-	out.Write32(uint32(ldr.SymDynid(rs)))
-
-	var v uint32
-	switch rt {
-	default:
-		// unsupported relocation type
-		return false
-
-	case objabi.R_DWARFSECREF:
-		v = ld.IMAGE_REL_ARM_SECREL
-
-	case objabi.R_ADDR:
-		v = ld.IMAGE_REL_ARM_ADDR32
-
-	case objabi.R_PEIMAGEOFF:
-		v = ld.IMAGE_REL_ARM_ADDR32NB
-	}
-
-	out.Write16(uint16(v))
-
-	return true
+	return false
 }
 
 // sign extend a 24-bit integer.