[maintainer] Workaround: mariadb55-client and other ports using libmysqlclient.so

[Alexandr Kovalenko]

Hello,

Just want to notice you that build of ports which depend on
libmysqlclient.so from MariaDB 5.5.33a is broken now on anything which
is older than OSVERSION 1000052 (i.e. 9.x and older 10.x), 10-BETA1
and 11-CURRENT are not affected. This happened due to introduction of
libexecinfo dependency. Sorry about that :(

The simpliest temporary workaround is, of course to create symlink:

ln -sf /usr/local/lib/libexecinfo.so /usr/lib

I'm working on a _proper_ solution with upstream now and will submit
proper fix as soon as possible.

Cheers,
Alexandr.