Update ci.yml

Add cygwin testing

Author: jeremyd2019

.github/workflows/ci.yml

@@ -1,6 +1,6 @@
 name: CI
 
-on: [push]
+on: [push, workflow_dispatch]
 
 jobs:
 
@@ -36,3 +36,52 @@ jobs:
         bin/package make -j5 &&
         : default regression tests with SHOPT_SCRIPTONLY enabled &&
         script -q -e -c "bin/shtests"
+
+  Cygwin:
+    name: Cygwin
+    runs-on: windows-latest
+    env:
+      CHERE_INVOKING: 1
+      CYGWIN_NOWINPATH: 1
+      CC: gcc
+      HOSTTYPE: cygwin.i386-64
+    defaults:
+      run:
+        shell: bash -leo pipefail -o igncr {0}
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@main
+    - name: Install Cygwin
+      uses: cygwin/cygwin-install-action@master
+      with:
+        packages: gcc-core gcc-g++ git libiconv-devel ncurses
+    - name: Git reset
+      run: |
+        git config --global --add safe.directory "$(pwd)" && git reset --hard
+    - name: Build
+      run: bin/package make -j2 HOSTTYPE=$HOSTTYPE
+    - name: Regression tests
+      run: |
+        PS4="$PS4[ci.yml] "
+        set -o xtrace
+        export TZ=UTC
+        ulimit -n 1024
+        : default regression tests &&
+        : hangs: script -q -e -c "bin/package test HOSTTYPE=$HOSTTYPE" &&
+        script -q -e -c "bin/shtests HOSTTYPE=$HOSTTYPE" &&
+        : regression tests with OS-provided multibyte locales &&
+        LANG=en_US.utf8 script -q -e -c "bin/shtests --locale --nocompile HOSTTYPE=$HOSTTYPE" &&
+        : disable most SHOPTs, rebuild ksh &&
+        sed --regexp-extended --in-place=.orig \
+          '/^SHOPT (AUDIT|BGX|BRACEPAT|DEVFD|DYNAMIC|EDPREDICT|ESH|FIXEDARRAY|HISTEXPAND|MULTIBYTE|NAMESPACE|OPTIMIZE|SPAWN|STATS|SUID_EXEC|VSH)=/ s/=1?/=0/' \
+          src/cmd/ksh93/SHOPT.sh &&
+        bin/package make -j2 HOSTTYPE=$HOSTTYPE &&
+        : default regression tests with SHOPTs disabled &&
+        script -q -e -c "bin/shtests HOSTTYPE=$HOSTTYPE" &&
+        : enable SHOPT_SCRIPTONLY, rebuild ksh &&
+        sed --regexp-extended --in-place=.orig \
+          '/^SHOPT SCRIPTONLY=/ s/=0?/=1/' \
+          src/cmd/ksh93/SHOPT.sh &&
+        bin/package make -j2 HOSTTYPE=$HOSTTYPE &&
+        : default regression tests with SHOPT_SCRIPTONLY enabled &&
+        script -q -e -c "bin/shtests HOSTTYPE=$HOSTTYPE"