Cocoa: Make the next-highest window gain focus when a window is closing.

(if the closed window wasn't the foreground, this is effectively a no-op.)

--HG--
extra : rebase_source : e87546ce8bcfc1b3e21631b8ef6a1264d3f499d6
Added a FIXME discussion to last commit.
Backed out hg changeset 7f26fd1df927; docs were wrong, not the code.
Fixed return value documentation for SDL_HapticUpdateEffect().

It was a cut-and-paste error from SDL_HapticNewEffect(), right above it.