Fix typo in SIZEOF_WCHAR_T test.

This fixes compilation under the platforms where SIZEOF_WCHAR_T != 4 (probably
Windows only).

Closes #11994.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@64156 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/strconv.cpp

@@ -1676,7 +1676,7 @@ wxMBConv_iconv::wxMBConv_iconv(const wxChar *name)
         {
 #if SIZEOF_WCHAR_T == 4
             _T("UCS-4"),
-#elif SIZEOF_WCHAR_T = 2
+#elif SIZEOF_WCHAR_T == 2
             _T("UCS-2"),
 #endif
             NULL