makepanda: Add _d suffix to .pyd files in debug mode on Windows

Fixes #1566

makepanda/makepandacore.py

@@ -3500,10 +3500,16 @@ def GetExtensionSuffix():
     target = GetTarget()
 
     if sys.version_info >= (3, 5) and target == 'windows':
+        if GetOptimize() <= 2:
+            dllext = '_d'
+        else:
+            dllext = ''
+
         if GetTargetArch() == 'x64':
-            return '.cp%d%d-win_amd64.pyd' % (sys.version_info[:2])
+            return dllext + '.cp%d%d-win_amd64.pyd' % (sys.version_info[:2])
         else:
-            return '.cp%d%d-win32.pyd' % (sys.version_info[:2])
+            return dllext + '.cp%d%d-win32.pyd' % (sys.version_info[:2])
+
     elif sys.version_info >= (3, 0):
         import _imp
         return _imp.extension_suffixes()[0]