remove cryptogrpahy step, as they ship wheels now

Signed-off-by: Kenneth Reitz <me@kennethreitz.org>

bin/compile

@@ -186,10 +186,6 @@ source "$BIN_DIR/steps/mercurial"
 # shellcheck source=bin/steps/pylibmc
 source "$BIN_DIR/steps/pylibmc"
 
-# Libffi support.
-# shellcheck source=bin/steps/cryptography
-source "$BIN_DIR/steps/cryptography"
-
 # Support for Geo libraries.
 # shellcheck source=bin/steps/geo-libs
 sub_env "$BIN_DIR/steps/geo-libs"

bin/steps/cryptography

@@ -1,38 +0,0 @@
-#!/usr/bin/env bash
-
-# This script serves as the cffi build step of the
-# [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
-# compiler.
-#
-# A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
-# adapter between a Python application and Heroku's runtime.
-#
-# This script is invoked by [`bin/compile`](/).
-
-if [[ "$STACK" == "heroku-16" ]]; then
-    # libffi is pre-installed in the stack image so there is no need to vendor it.
-    return 0
-fi
-
-# The location of the pre-compiled libffi binary.
-VENDORED_LIBFFI="${VENDOR_URL}/libraries/vendor/libffi.tar.gz"
-
-PKG_CONFIG_PATH="/app/.heroku/vendor/lib/pkgconfig:$PKG_CONFIG_PATH"
-
-# Syntax sugar.
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
-
-# If a package using cffi exists within requirements, use vendored libffi.
-if (pip-grep -s requirements.txt argon2-cffi bcrypt cffi cryptography django[argon2] Django[argon2] django[bcrypt] Django[bcrypt] PyNaCl pyOpenSSL PyOpenSSL requests[security] misaka &> /dev/null) then
-
-  if [ ! -d ".heroku/vendor/lib/libffi-3.1" ]; then
-    echo "-----> Noticed cffi. Bootstrapping libffi."
-    mkdir -p .heroku/vendor
-    # Download and extract libffi into target vendor directory.
-    curl "$VENDORED_LIBFFI" -s | tar zxv -C .heroku/vendor &> /dev/null
-  fi
-
-  LIBFFI=$(pwd)/vendor
-  export LIBFFI
-fi