Actually fix issue 3659.

check for cp932 using ::IsValidCodePage before creating the wxCSConv
if it is possible for linux distro or mac to remove the euc_jap cp from install a similar check may be added in WxUtils.cpp

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@6928 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Core/DolphinWX/Src/WxUtils.h

@@ -20,6 +20,8 @@
 
 namespace WxUtils {
 
+wxCSConv * SJISConv();
+
 // Launch a file according to its mime type
 void Launch(const char *filename);