[milo] build_source -> buildSource.

milo/buildsource/swarming/buildinfo.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 swarming
 
 import (
         "strconv"
         "strings"
         "unicode/utf8"
@@ skipping 249 matching lines @@
         }
 
         lastChar, lastCharSize := utf8.DecodeLastRuneInString(taskID)
         v, err := strconv.ParseUint(string(lastChar), 16, 8)
         if err != nil {
                 return "", errors.Annotate(err, "failed to parse hex from rune: %r", lastChar).Err()
         }
 
         return taskID[:len(taskID)-lastCharSize] + strconv.FormatUint((v|uint64(tryNumber)), 16), nil
 }