The llvm::OptTable::findNearest bug fixed in
https://reviews.llvm.org/D41873 manifested itself as the following
erroneous message when invoking Clang:
clang -version clang-6.0: error: unknown argument '-version', did you mean 'version'?
Add a test to catch any future regressions to the now correct behavior,
which asks "did you mean '--version'?".
Test Plan: check-clang