myodbc_end is really only usable during Windows DLL unload, since it's not
connection-specific and not thread-safe either.  This bit of brain fade
accounts for our bug #185343 and several bugs filed at mysql.com.

Furthermore, my_end() isn't exported from libmysqlclient anymore.
Hence, best fix is to turn the function into a no-op.

diff -up mysql-connector-odbc-5.2.6-src.orig/driver/dll.c mysql-connector-odbc-5.2.6-src/driver/dll.c
--- mysql-connector-odbc-5.2.6-src.orig/driver/dll.c	2013-09-25 18:59:00.000000000 +0200
+++ mysql-connector-odbc-5.2.6-src/driver/dll.c	2014-01-24 10:16:45.729228067 +0100
@@ -96,6 +96,7 @@ void myodbc_init(void)
 */
 void myodbc_end()
 {
+#if 0
   if (!--myodbc_inited)
   {
     x_free(decimal_point);
@@ -123,6 +124,7 @@ void myodbc_end()
     my_end(0);
 #endif
   }
+#endif
 }