Add goog.FEATURESET_YEAR define
Add goog.FEATURESET_YEAR define

This is intended to be the "one define to rule them all".  We will gradually start defaulting most of the other defines inside and outside of Closure Library based on this value, as well as eventually give it special treatment in Closure Compiler.

RELNOTES[NEW]: Add goog.FEATURESET_YEAR define.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=241982945

google/closure-library,google/closure-library,google/closure-library,google/closure-library,lucidsoftware/closure-library,google/closure-library,lucidsoftware/closure-library,lucidsoftware/closure-library,lucidsoftware/closure-library