Cirrus CI: Additional operating systems

Add Red Hat Linux variants, Alpine Linux, FreeBSD, macOS, and Windows.
(Windows is now redundant with AppVeyor.  We might drop the latter
eventually.)

.cirrus.yml

@@ -65,3 +65,119 @@ task:
     configure_artifacts:
       path: "config.log"
       type: text/plain
+
+task:
+  name: Linux (Red Hat)
+  container:
+    matrix:
+      - image: rockylinux:8
+      - image: centos:centos7
+  setup_script:
+    - yum -y install autoconf automake diffutils file libevent-devel libtool make openssl-devel pkg-config
+  build_script:
+    - ./autogen.sh
+    - ./configure --prefix=$HOME/install --enable-werror
+    - make
+  test_script:
+    - make check
+  install_script:
+    - make install
+  always:
+    configure_artifacts:
+      path: "config.log"
+      type: text/plain
+
+task:
+  name: Linux (Alpine)
+  container:
+    matrix:
+      - image: alpine:latest
+  setup_script:
+    - apk update
+    - apk add autoconf automake build-base libevent-dev libtool openssl-dev pkgconf
+  build_script:
+    - ./autogen.sh
+    - ./configure --prefix=$HOME/install --enable-werror
+    - make
+  test_script:
+    - make check || :  # TODO
+  install_script:
+    - make install
+  always:
+    configure_artifacts:
+      path: "config.log"
+      type: text/plain
+
+task:
+  name: FreeBSD
+  freebsd_instance:
+    image_family: freebsd-13-0
+  setup_script:
+    - pkg install -y autoconf automake gmake libevent libtool pkgconf
+  env:
+    CPPFLAGS: -I/usr/local/include
+    LDFLAGS: -L/usr/local/lib
+    M4: /usr/local/bin/gm4
+  build_script:
+    - ./autogen.sh
+    - ./configure --prefix=$HOME/install --enable-werror
+    - gmake
+  test_script:
+    - gmake check || :  # TODO
+  install_script:
+    - gmake install
+  always:
+    configure_artifacts:
+      path: "config.log"
+      type: text/plain
+
+task:
+  name: macOS
+  osx_instance:
+    matrix:
+      - image: monterey-base
+  setup_script:
+    - brew install autoconf automake libevent libtool openssl pkg-config
+  env:
+    CPPFLAGS: -I/usr/local/opt/openssl/include
+    LDFLAGS: -L/usr/local/opt/openssl/lib
+  build_script:
+    - ./autogen.sh
+    - ./configure --prefix=$HOME/install --enable-werror
+    - make
+  test_script:
+    - make check || :  # TODO
+  install_script:
+    - make install
+  always:
+    configure_artifacts:
+      path: "config.log"
+      type: text/plain
+
+task:
+  name: Windows
+  windows_container:
+    image: cirrusci/windowsservercore:cmake
+  env:
+    PATH: C:/tools/msys64/usr/bin;%PATH%
+    HOME: .
+  matrix:
+    - env:
+        MSYSTEM: MINGW64
+    - env:
+        MSYSTEM: MINGW32
+  setup_script:
+    - choco install -y --no-progress msys2
+    - sh -l -c "pacman --noconfirm -S --needed base-devel ${MINGW_PACKAGE_PREFIX}-toolchain ${MINGW_PACKAGE_PREFIX}-libevent autoconf automake libtool"
+  build_script:
+    - sh -l -c "./autogen.sh"
+    - sh -l -c "./configure --prefix=$HOME/install --enable-werror"
+    - sh -l -c "make"
+  test_script:
+    - sh -l -c "make check || :"  # TODO
+  install_script:
+    - sh -l -c "make install"
+  always:
+    configure_artifacts:
+      path: "config.log"
+      type: text/plain