[Bug localedata/10871] ru_RU: 'mon' array should contain both nominative and genitive cases

[Keld Simonsen]

Hi 

I would ask that our changes are backwards compatible, so that we need not change 
the existing data, just addin new data, (and changing the date format spec).

Something like the %B is the nominative case, %OB is the genitive case, and then
the full date spec is using %OB for the month names when required.

And the alt_mon is an optional keyword, and general. I believe these changes are
getting their way into both POSIX and i18n 30112 standards.

Best regads
keld