When a cc module is built against a stub, compiler passes version macro
of the stub lib. Version macro should be numeric, so codenames or
"current" should be mapped to numbers just like how ndkstubgen maps to.
* "current" -> future (10000)
* codenames -> look up api_level.json
* otherwise -> cast to int
Bug: 179329813
Test: m / soong test / manually check the output build.ninja
Change-Id: Ic0e1dd904984e161694a0b77fad5559c06a4462f
11b0fbdbf6