Bug#405773: mysql support in apr-util

[Stefan Fritsch <sf@sfritsch.de>]

Before mysql support can be added to apr-util, either

1) php must link against libmysqlclient_r.so instead of 
libmysqlclient.so

or

2) libmysqlclient_r.so and libmysqlclient.so must be changed so that 
they use differently versioned symbols

After talking with seanius on #debian-devel, it is possible that 2) 
will happen with the move to mysql5.1/libmysqlclient16