Fix Cygw32 build

* src/pdumper.c (dump_mm_heap_cb_release): Avoid NULL pointer
dereference.
* src/w32dwrite.c (INITGUID) [CYGWIN]: Don't define for Cygwin.
* src/w32menu.c (w32_popup_dialog): Fix Cygw32 build.  (Bug#74312)

1 files changed, 7 insertions, 4 deletions

diff --git a/src/pdumper.c b/src/pdumper.c
index c888b659dde..c0b36b1ca44 100644
--- a/src/pdumper.c
+++ b/src/pdumper.c
@@ -4853,11 +4853,14 @@ struct dump_memory_map_heap_control_block
 static void
 dump_mm_heap_cb_release (struct dump_memory_map_heap_control_block *cb)
 {
-  eassert (cb->refcount > 0);
-  if (--cb->refcount == 0)
+  if (cb)
     {
-      free (cb->mem);
-      free (cb);
+      eassert (cb->refcount > 0);
+      if (--cb->refcount == 0)
+        {
+          free (cb->mem);
+          free (cb);
+        }
     }
 }