This is increasingly difficult to maintain, and has very limited
benefit. Modern coprocessors with enough horsepower to run Java
applications can use the Gradle or Bazel build systems instead.
-DUSE_SYSTEM_EIGEN now only removes include paths for Eigen instead of
drake as well.
The USE_VCPKG flags were renamed to USE_SYSTEM since they seem general
enough for that to work (the find_package() commands work the same way
on Arch).
The system libuv CMake build now works with Linux libuv as well.
