Revert "Update fputcsv() to escape all characters equally."

On second thoughts, while the behaviour _is_ broken, this isn't the right fix.

This reverts commit 9b5cb0e8059b1e8bec096067491ed8d75f878938.
Revert "Apply the fputcsv test fix to SplFileObject_fputcsv.phpt. Mea culpa."

This reverts commit 0510701474e8d99b5b30139b5599e44f9b555a5a.