[PATCH setup] When in unattended mode, ignore attempts to close via GUI

[Jon Turney]

Perhaps this should be controlled by a separate option, but making setup
non-interactive seems like a reasonable fit with the intent of
'--quiet-mode'.

This doesn't stop the installer being killed by TerminateProcess().

Addresses: https://cygwin.com/pipermail/cygwin/2021-November/250079.html
---
 propsheet.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/propsheet.cc b/propsheet.cc
index 00b2ad8..742e5da 100644
--- a/propsheet.cc
+++ b/propsheet.cc
@@ -161,6 +161,8 @@ static LRESULT CALLBACK PropSheetWndProc (HWND hwnd, UINT 
uMsg,
       if (wParam != 2)
        break;
     areyousure:
+      if (unattended_mode == unattended)
+        return 0;
       if (mbox(hwnd, IDS_CONFIRM_EXIT, MB_YESNO) == IDNO)
        return 0;
       break;
-- 
2.34.1