Revert "add fenv cache to task struct (#51288)" (#56982)
This reverts commit 12aa9dea03a8a6bbe2891d3ca6ce34a21ec84734.
un-fixes #51277
Alternatively, we could add a flag for whether the state is non-default
so we know whether `fesetenv` is necessary, if this behavior is
considered desireable.
