Drop CircleCI.

.circleci/build-and-test.sh

diff --git a/.circleci/build-and-test.sh b/.circleci/build-and-test.sh
deleted file mode 100755
index b99c5e3..0000000
--- a/.circleci/build-and-test.sh
+++ /dev/null
@@ -1,15 +0,0 @@
-#!/bin/bash
-
-#
-# common build & test steps for CircleCI jobs
-#
-
-uname -a
-cmake --version
-ninja --version
-
-mkdir build
-cd build
-cmake -G Ninja -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} -DNN_ENABLE_COVERAGE=${COVERAGE:-OFF} ..
-ninja
-env CTEST_OUTPUT_ON_FAILURE=1 ninja test

.circleci/codecov.sh

diff --git a/.circleci/codecov.sh b/.circleci/codecov.sh
deleted file mode 100755
index 08922ae..0000000
--- a/.circleci/codecov.sh
+++ /dev/null
@@ -1,20 +0,0 @@
-#!/bin/bash
-
-# Copyright 2018 Garrett D'Amore <garrett@damore.org>
-# Copyright 2018 Capitar IT Group BV <info@capitar.com>
-#
-# This software is supplied under the terms of the MIT License, a
-# copy of which should be located in the distribution where this
-# file was obtained (LICENSE.txt).  A copy of the license may also be
-# found online at https://opensource.org/licenses/MIT.
-
-if [ "${COVERAGE}" != ON ]
-then
-	echo "Code coverage not enabled."
-	exit 0
-fi
-
-GCOV=${GCOV:-gcov}
-
-bash <(curl -s https://codecov.io/bash) -x ${GCOV} || echo "Codecov did not collect coverage"
-echo 0

.circleci/config.yml

diff --git a/.circleci/config.yml b/.circleci/config.yml
deleted file mode 100644
index adf1408..0000000
--- a/.circleci/config.yml
+++ /dev/null
@@ -1,84 +0,0 @@
-#
-# CircleCI 2.0 configuration. This was borrowed from NNG, but is adjusted
-# for libnanomsg.  (We don't need mbedTLS or use clang-format, for example.)
-#
-version: 2.0
-jobs:
-  "clang6 - build, test":
-    docker:
-      - image: ubuntu:16.04
-        environment:
-          CC: clang-6.0
-          CXX: clang++-6.0
-          CTEST_OUTPUT_ON_FAILURE: 1
-    steps:
-      - checkout
-      - run: apt-get update -qq
-      - run: apt-get install -y software-properties-common
-      - run: apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-6.0 main"
-      - run: apt-get update -qq
-      - run: >
-          apt-get install -y --allow-unauthenticated
-          build-essential
-          asciidoctor
-          cmake
-          ninja-build
-          clang-6.0
-      - run: ./.circleci/build-and-test.sh
-
-  "gcc8 - build, test":
-    docker:
-      - image: ubuntu:16.04
-        environment:
-          CC: gcc-8
-          CXX: g++-8
-          GCOV: gcov-8
-          CTEST_OUTPUT_ON_FAILURE: 1
-    steps:
-      - checkout
-      - run: apt-get update -qq
-      - run: apt-get install -y software-properties-common
-      - run: add-apt-repository ppa:ubuntu-toolchain-r/test
-      - run: apt-get update -qq
-      - run: >
-          apt-get install -y --allow-unauthenticated
-          build-essential
-          asciidoctor
-          cmake
-          ninja-build
-          gcc-8
-          g++-8
-      - run: ./.circleci/build-and-test.sh
-
-  "gcc - coverage":
-    docker:
-      - image: ubuntu:16.04
-        environment:
-          CC: gcc
-          CXX: g++
-          COVERAGE: "ON"
-          GCOV: gcov
-          CTEST_OUTPUT_ON_FAILURE: 1
-    steps:
-      - checkout
-      - run: apt-get update -qq
-      - run: apt-get install -y software-properties-common
-      - run: add-apt-repository ppa:ubuntu-toolchain-r/test
-      - run: apt-get update -qq
-      - run: >
-          apt-get install -y --allow-unauthenticated
-          build-essential
-          curl
-          asciidoctor
-          cmake
-          ninja-build
-      - run: ./.circleci/build-and-test.sh
-      - run: ./.circleci/codecov.sh
-
-workflows:
-  version: 2
-  build_and_test:
-    jobs:
-      - "clang6 - build, test"
-      - "gcc8 - build, test"
-      - "gcc - coverage"