Add language_names/ to dist.

[bentley]

With this commit, “make dist” includes the files under language_names/ in the tarball under dist/.

[coveralls]

Pull Request Test Coverage Report for Build 1065

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 45.123%

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Totals
Change from base Build 1063:	0.0%
Covered Lines:	1057
Relevant Lines:	2111

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💛 - Coveralls