always use wxString::operator[](size_t) - wxWin doesn't compile without it anyhow

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@4219 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/string.h

@@ -370,14 +370,9 @@ public:
     wxChar& Last()
       { wxASSERT( !IsEmpty() ); CopyBeforeWrite(); return m_pchData[Len()-1]; }
 
-    // under Unix it is tested with configure, assume it works on other
-    // platforms (there might be overloading problems if size_t and int are
-    // the same type)
-#if !defined(__UNIX__) || wxUSE_SIZE_T_STRING_OPERATOR
     // operator version of GetChar
     wxChar  operator[](size_t n) const
       { ASSERT_VALID_INDEX( n ); return m_pchData[n]; }
-#endif
 
     // operator version of GetChar
     wxChar  operator[](int n) const