Fixed building Windows DLL with latest native Cygwin tools

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%40438

ltconfig

@@ -186,7 +186,7 @@ enable_shared=yes
 enable_static=yes
 enable_fast_install=yes
 enable_dlopen=unknown
-enable_win32_dll=no
+enable_win32_dll=yes
 ltmain=
 silent=
 srcdir=