cmd/link: use ctxt.{Lookup,ROLookup} in favour of function versions of same

cmd/link: use ctxt.{Lookup,ROLookup} in favour of function versions of same

Done with two eg templates:

package p

import (
	"cmd/link/internal/ld"
)

func before(ctxt *ld.Link, name string, v int) *ld.Symbol {
	return ld.Linklookup(ctxt, name, v)
}
func after(ctxt *ld.Link, name string, v int) *ld.Symbol {
	return ctxt.Syms.Lookup(name, v)
}

package p

import (
	"cmd/link/internal/ld"
)

func before(ctxt *ld.Link, name string, v int) *ld.Symbol {
	return ld.Linkrlookup(ctxt, name, v)
}
func after(ctxt *ld.Link, name string, v int) *ld.Symbol {
	return ctxt.Syms.ROLookup(name, v)
}

Change-Id: I00647dbf62294557bd24c29ad1f108fc786335f1
Reviewed-on: https://go-review.googlesource.com/29343
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>