Add msys-based Windows build to CI

.cirrus.yml

@@ -50,3 +50,12 @@ cygwin_task:
     - c:\tools\cygwin\cygwinsetup -q -P binutils,gcc-core
   compile_script:
     - c:\tools\cygwin\bin\bash --login "%CD%\scripts\build.sh"
+msys_task:
+  windows_container:
+    image: cirrusci/windowsservercore:cmake
+    os_version: 2019
+  setup_script:
+    - set PATH=c:\tools\msys64\bin;c:\tools\msys64\usr\bin;%PATH%
+    - pacman --noconfirm -S gcc
+  compile_script:
+    - c:\tools\msys64\usr\bin\bash --login "%CD%\scripts\build.sh"

README.adoc

@@ -23,6 +23,7 @@ system C compiler. 64-bit and 32-bit builds work. Supported operating systems:
   ** Alpine Linux (gcc)
   ** Void Linux (gcc)
   ** Cygwin (gcc)
+  ** Msys (gcc)
 * BSD
   ** FreeBSD (clang)
   ** OpenBSD (clang)

scripts/build.sh

@@ -2,7 +2,7 @@
 set -eu
 os="$(uname | tr A-Z- a-z_)"
 case $os in
-cygwin*)
+cygwin*|msys*)
     os=linux
     ;;
 esac