The bug is caused due to the original IndexStmt that DefineIndex receives
being overwritten when processing the INCLUDE columns. Use separate list of
index params to propagate to child tables. Add tests covering this case.

Amit Langote and Alexander Korotkov.

Re-commit 5c6110c6 because it discovered a bug
fixed in c266ed31

Discussion: https://www.postgresql.org/message-id/CAJGNTeO%3DBguEyG8wxMpU_Vgvg3nGGzy71zUQ0RpzEn_mb0bSWA%40mail.gmail.com