[Patch] Add C++14 feature querying macro `cxx_digit_separators` describing support for "Single-Quotation-Mark as a Digit Separator"

[Michel Morin]

Richard Smith wrote:
> Please also update the documentation to suggest using this macro
> to detect the feature.

I updated LanguageExtensions.rst for `__has_feature(cxx_digit_separators)` in
cxx_digit_separators.patch (the patch in the first mail):

+C++1y digit separators
+^^^^^^^^^^^^^^^^^^^^^^
+
+Use ``__has_feature(cxx_digit_separators)`` or
+``__has_extension(cxx_digit_separators)`` to determine if support for
+digit separators using single quotes (for instance, ``10'000``) is enabled.

Do you mean adding the suggestion of using `__cpp_digit_separators` to
the above description, like

+Use ``__has_feature(cxx_digit_separators)``,
+``__has_extension(cxx_digit_separators)`` or
+``__cpp_digit_separators >= 201309`` to determine if support for
+digit separators using single quotes (for instance, ``10'000``) is enabled.

or updating other place?


Regards,
Michel