fix recently introduced memory leak of m_conv (bug 1466559)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38616 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/fileconf.cpp

@@ -568,6 +568,8 @@ void wxFileConfig::CleanUp()
 
 wxFileConfig::~wxFileConfig()
 {
+    delete m_conv;
+
     Flush();
 
     CleanUp();