Use constexpr instead of DUNE_CONSTEXPR

As your current series of patches replaces the use of DUNE_CONSTEXPR the corresponding header should also be deprecated.

Added 1 commit:

• 2df8a230 - deprecate std/consexpr.hh header

@christi I added a deprecation warning to the header

Added 1 commit:

• 9cd317f6 - [Cleanup] Remove superfluous include to constexpr.hh

mentioned in commit 834b14c0

Status changed to merged

Mentioned in commit 834b14c0