Make ant example's path handling work on Windows
Make ant example's path handling work on Windows

https://github.com/google/error-prone/commit/3f2ca43e53266e84e17e4fb3f34888be5cb29293#commitcomment-30383244

MOE_MIGRATED_REVID=211572444

google/error-prone,cushon/error-prone,google/error-prone,cushon/error-prone,cushon/error-prone,cushon/error-prone