[dev.unified] cmd/compile: only sort symbols by name and package path

Since CL 393715, the path of package being compiled is now always known,
so symbols can be sorted by package path instead of package height.

Updates #51734

Change-Id: Ie543e2fdef4b93f3f0b97c6bcec0a4dcff788f2c
Reviewed-on: https://go-review.googlesource.com/c/go/+/410654
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

src/cmd/compile/internal/types/sym.go

@@ -97,14 +97,7 @@ func (sym *Sym) LinksymABI(abi obj.ABI) *obj.LSym {
 // Less reports whether symbol a is ordered before symbol b.
 //
 // Symbols are ordered exported before non-exported, then by name, and
-// finally (for non-exported symbols) by package height and path.
-//
-// Ordering by package height is necessary to establish a consistent
-// ordering for non-exported names with the same spelling but from
-// different packages. We don't necessarily know the path for the
-// package being compiled, but by definition it will have a height
-// greater than any other packages seen within the compilation unit.
-// For more background, see issue #24693.
+// finally (for non-exported symbols) by package path.
 func (a *Sym) Less(b *Sym) bool {
 	if a == b {
 		return false
@@ -131,9 +124,6 @@ func (a *Sym) Less(b *Sym) bool {
 		return a.Name < b.Name
 	}
 	if !ea {
-		if a.Pkg.Height != b.Pkg.Height {
-			return a.Pkg.Height < b.Pkg.Height
-		}
 		return a.Pkg.Path < b.Pkg.Path
 	}
 	return false