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/x11/bitmap.cpp

@@ -1072,8 +1072,7 @@ void wxBitmap::SetPalette(const wxPalette& palette)
                 wxT("cannot set palette for bitmap of this depth"));
 
     AllocExclusive();
-    delete M_BMPDATA->m_palette;
-    M_BMPDATA->m_palette = NULL;
+    wxDELETE(M_BMPDATA->m_palette);
 
     if (!palette.Ok()) return;