Depending on where an exception is raised inside a compiler's
`execute_command`, the `stdout` variable may not be assigned. In this case, the
finally handler would fail with an `UnboundLocalError`, hiding the true cause
of the exception. This change adds a new variable, `stdout_name`, which is
populated once we've actually created the file. After this, the `CompilerError`
is successfully raised with the contents of the true error.