add "ba" locale to gettextPlurals()

[aprocom]

[rubenv]

I don't see this locale listed in any of the known plural rule databases, though I did find that it's an ISO 639-1 language (good!).

Do you have any reference on this plural rule?

[rubenv]

Obviously not a Bashkir speaker, but some research leads me to believe that Bashkir does have plural forms:

Bashkort has two numbers: singular and plural. The plural is formed by adding the suffix –lar/-dar/ -tar to the singular root, e.g., студент ‘student’, студенттар‘ student (from http://aboutworldlanguages.com/bashkir)

Based on this the proposed plural rule (with just 1 form) doesn't look correct to me.