envconfig: remove unused parse_datafile()

The cross-file cleanup meant this function is no longer used, so remove it.

mesonbuild/envconfig.py

@@ -68,16 +68,6 @@ CPU_FAMILES_64_BIT = [
 ]
 
 class MesonConfigFile:
-    @classmethod
-    def parse_datafile(cls, filename):
-        config = configparser.ConfigParser()
-        try:
-            with open(filename, 'r') as f:
-                config.read_file(f, filename)
-        except FileNotFoundError:
-            raise EnvironmentException('File not found: %s.' % filename)
-        return cls.from_config_parser(config)
-
     @classmethod
     def from_config_parser(cls, parser: configparser.ConfigParser):
         out = {}