0.2.0 crates.io release

• Removed the compile-time Linux version check, and replaced it with a Cargo feature.

  The Linux version check was overly restrictive, even on systems that did have the right kernel
  version installed but had older headers in /usr/include/linux. Beyond that, this check made it
  more difficult to compile on a different host than what's targeted.

  There is now a linux4_14 feature flag on userfaultfd-sys, which turns on and tests the extra
  constants available in that version. Since userfaultfd did not make use of any of those newer
  features, it doesn't have a feature flag yet.

  Applications should take care when initializing with UffdBuilder to specify the features and
  ioctls they require, so that an unsupported version will be detected at runtime.

0.1.0 crates.io release

0.1.0 (2020-04-07)

• Initial public release of userfaultfd-rs.