CI: add .circleci/config.yml

Assisted-by: Gabriel Simmer

Closes #7239

.circleci/config.yml

@@ -0,0 +1,51 @@
+# Use the latest 2.1 version of CircleCI pipeline process engine. See: https://circleci.com/docs/2.0/configuration-reference
+version: 2.1
+
+commands:
+  configure:
+    steps:
+      - run:
+          command: |
+            ./buildconf
+            ./configure --enable-warnings --enable-werror --with-openssl
+
+  build:
+    steps:
+      - run: make
+
+  test:
+    steps:
+      - run: make test-nonflaky
+
+executors:
+  ubuntu:
+    machine:
+      image: ubuntu-2004:202010-01
+
+jobs:
+  basic:
+    executor: ubuntu
+    steps:
+      - checkout
+      - configure
+      - build
+      - test
+
+  arm:
+    machine:
+      image: ubuntu-2004:202101-01
+    resource_class: arm.medium
+    steps:
+      - checkout
+      - configure
+      - build
+      - test
+
+workflows:
+  x86-openssl:
+    jobs:
+      - basic
+
+  arm-openssl:
+    jobs:
+      - arm