parser_test only needed the directory-names for
the tests to run. This replaces f.Readdir() with
f.Readdirnames() to only return the names.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 9e63b0d0f9530a0a7d6445606062b8ca99793792
Component: engine