P2441 Fix "In that case"

[jensmaurer]

Replace "In that case..." with "If defined, ..."

"In that case" is ambiguous, because it might refer to any of three preceding conditions, or the combination of them.

Fix in P2441 and the existing views::join.

[timsong-cpp]

There are five "In that case"s in the current draft.

[JohelEGP]

Searching https://eel.is/c++draft/full for "in that case" shows 13 matches, 9 outside of notes.

[eisenwave]

To be clear, we're talking about cases like https://eel.is/c++draft/range.join.with.iterator#2

The member typedef-name iterator_category is defined if and only if ref-is-glvalue is true, and Base and InnerBase each model forward_range. In that case, iterator::iterator_category is defined as follows:

There are 8 such cases in [ranges].