Drop static_mock.go

[mattn]

The current implementation of static_mock.go is not sufficient because it does not expose all the constants/variables and functions exposed by the cgo enabled sqlite3 package as dummies. However, adding dummy constants/variables and functions to this would require maintenance effort to ensure that go-sqlite3 can be built with !cgo in the future.

My opinion is the drop of statck_mock.go. Anyone's opinion?