cmOutputConverter: remove unused code

Remove old ConvertToRelativePath function now that all clients have
migrated to the new signature.

Source/cmOutputConverter.cxx

@@ -76,15 +76,6 @@ static bool cmOutputConverterNotAbove(const char* a, const char* b)
           cmSystemTools::IsSubDirectory(a, b));
 }
 
-std::string cmOutputConverter::ConvertToRelativePath(
-  const std::vector<std::string>& local, const std::string& in_remote,
-  bool force) const
-{
-  std::string local_path = cmSystemTools::JoinPath(local);
-  return force ? this->ForceToRelativePath(local_path, in_remote)
-               : this->ConvertToRelativePath(local_path, in_remote);
-}
-
 std::string cmOutputConverter::ConvertToRelativePath(
   std::string const& local_path, std::string const& remote_path) const
 {

Source/cmOutputConverter.h

@@ -99,17 +99,6 @@ public:
   };
   static FortranFormat GetFortranFormat(const char* value);
 
-  /**
-   * Convert the given remote path to a relative path with respect to
-   * the given local path.  The local path must be given in component
-   * form (see SystemTools::SplitPath) without a trailing slash.  The
-   * remote path must use forward slashes and not already be escaped
-   * or quoted.
-   */
-  std::string ConvertToRelativePath(const std::vector<std::string>& local,
-                                    const std::string& in_remote,
-                                    bool force = false) const;
-
   /**
    * Convert the given remote path to a relative path with respect to
    * the given local path.  Both paths must use forward slashes and not