'Adds a configuration to a file.
Args:
path: Relative path to the file.
config: Name of configuration to add.
attrs: Dict of configuration attributes; may be None.
tools: List of tools (strings or Tool objects); may be None.
Raises:
ValueError: Relative path does not match any file added via AddFiles().'

def AddFileConfig(self, path, config, attrs=None, tools=None):

    parent = self.files_dict.get(path)
    if (not parent):
        raise ValueError(('AddFileConfig:    file    "%s"    not    in    project.' % path))
    spec = self._GetSpecForConfiguration('FileConfiguration', config, attrs, tools)
    parent.append(spec)
