Use wxDELETE() and wxDELETEA() when possible.

Use wxDELETE[A]() functions which automatically NULL out their arguments after
deleting them instead of doing it manually.

Closes #9685.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64656 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/propgrid/editors.cpp

@@ -1512,8 +1512,7 @@ END_EVENT_TABLE()
 
 wxSimpleCheckBox::~wxSimpleCheckBox()
 {
-    delete ms_doubleBuffer;
-    ms_doubleBuffer = NULL;
+    wxDELETE(ms_doubleBuffer);
 }
 
 wxBitmap* wxSimpleCheckBox::ms_doubleBuffer = NULL;