The code to implement new-style gccgo name mangling had a recipe that
    didn't quite match the one in the compiler (incorrect handling for
    '.'). This showed up as a failure in the gotools cgo test if the
    directory containing the test run included a "." character.
    
    Reviewed-on: https://go-review.googlesource.com/c/147917

From-SVN: r265981