[vpython] Fix PEP425 naming.

vpython/spec/match.go

 // Copyright 2017 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package spec
 
 import (
         "github.com/luci/luci-go/vpython/api/vpython"
 )
 
 // PackageMatches returns true if any of the match qualifiers in the supplied
 // package match at least one of the supplied PEP425 tags.
 //
 // As a special case, if the package doesn't specify any match tags, it will
 // always match regardless of the supplied PEP425 tags.
 //
 // See PEP425Matches for more information.
-func PackageMatches(pkg *vpython.Spec_Package, tags []*vpython.Pep425Tag) bool {
+func PackageMatches(pkg *vpython.Spec_Package, tags []*vpython.PEP425Tag) bool {
         if len(pkg.MatchTag) == 0 {
                 return true
         }
 
         for _, matchTag := range pkg.MatchTag {
                 if PEP425Matches(matchTag, tags) {
                         return true
                 }
         }
         return false
 }
 
 // PEP425Matches returns true if match matches at least one of the tags in tags.
 //
 // A match is determined if the non-zero fields in match equal the equivalent
 // fields in a tag.
-func PEP425Matches(match *vpython.Pep425Tag, tags []*vpython.Pep425Tag) bool {
+func PEP425Matches(match *vpython.PEP425Tag, tags []*vpython.PEP425Tag) bool {
         // Special case: empty match matches nothing.
         if match.IsZero() {
                 return false
         }
 
         for _, tag := range tags {
-                if v := match.Version; v != "" && tag.Version != v {
+                if v := match.Python; v != "" && tag.Python != v {
                         continue
                 }
                 if v := match.Abi; v != "" && tag.Abi != v {
                         continue
                 }
-                if v := match.Arch; v != "" && tag.Arch != v {
+                if v := match.Platform; v != "" && tag.Platform != v {
                         continue
                 }
                 return true
         }
 
         return false
 }