Add github msys2 workflow

.github/workflows/windows.yml

@@ -0,0 +1,17 @@
+on: push
+jobs:
+  build:
+    runs-on: windows-latest
+    steps:
+    - uses: msys2/setup-msys2@v2
+      with:
+        msystem: msys
+        install: gcc make diffutils
+    - uses: actions/checkout@v4
+    - shell: msys2 {0}
+      run: |
+        ./configure
+        gcc line.c
+        ./a.exe | od -t ax1
+        od -t ax1 test
+        make all check bootstrap

configure

@@ -122,7 +122,7 @@ case "$target" in
 	endfiles='"-l", "c", "-l", ":crtn.o"'
 	defines='"-D", "__builtin_stdarg_start(ap, last)=__builtin_va_start(ap, last)"'
 	;;
-*-*msys*)
+*-msys*)
 	startfiles='"-l", ":crt0.o"'
 	endfiles='"-l", "c", "-l", "msys-2.0", "-l", "kernel32"'
 	;;

line.c

@@ -0,0 +1,7 @@
+#include <stdio.h>
+int main(void) {
+	puts("hello");
+	FILE *f = fopen("test", "w");
+	fputs("hello", f);
+	fclose(f);
+}