Build warning on Clang with -Wdeprecated-redundant-constexpr-static-def

[stephenberry]

out-of-line definition of constexpr static data member is redundant in C++17 and is deprecated

Enabling -Wdeprecated-redundant-constexpr-static-def with warnings as errors causes fast_float to not build on Clang.

Fixing this should make the code cleaner as well.

[lemire]

@stephenberry pull request invited!

[stephenberry]

I think to support C++11 you would need macros around the old expressions. Do you want this?

[lemire]

The library is C++11 and we do not want to change this.

Using macros is acceptable.

[dalle]

I can't reproduce this issue anymore, any more details on versions used @stephenberry?

[stephenberry]

This issue was reported for version 6.1.3, perhaps someone fixed it. Are you making sure to build with C++17 or later?

[dalle]

This was fixed in #268 for release 6.1.5.

[dalle]

Thank you for your report, I'm closing this issue.