[flang] Move forall01 to ERROR_TESTS

That seems to be what was intended and it provides for better checking
of errors.

Original-commit: flang-compiler/f18@99376d77a07aa04173bd20dcc45d08b76cae4a73
Reviewed-on: https://github.com/flang-compiler/f18/pull/904
Tree-same-pre-rewrite: false