cast to proper type to avoid warning

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76291 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/string.cpp

@@ -1183,7 +1183,7 @@ wxString wxString::FromAscii(const char *ascii, size_t len)
             wxASSERT_MSG( c < 0x80,
                           wxT("Non-ASCII value passed to FromAscii().") );
 
-            *dest++ = (wchar_t)c;
+            *dest++ = static_cast<wxStringCharType>(c);
         }
     }