chore: import upstream snapshot with attribution

examples/c/openat.c

@@ -0,0 +1,10 @@
+#include <fcntl.h>
+#include <stdio.h>
+#include <errno.h>
+
+int main()
+{
+	int ret = openat(AT_FDCWD, "/dev/tty", 0x88102, 0);
+	printf("return value is %d and errno is %d\n", ret, errno);
+}
+