Deb: Make libmariadb3 to provide the libmysqlclient.so.XX links

For backwards compatibility reasons.

E.g. innotop builds against libmysqlclient.so and expects to find
a libmysqlclient.so.18 library and does not use libmariadb.so.3 even
when built from our own sources.

This commit mimics to dcfe6cb8

debian/control

@@ -46,8 +46,8 @@ Conflicts: mariadb-galera-server-10.0 (<< 10.0.5),
            mariadb-server-5.2,
            mariadb-server-5.3,
            mariadb-server-5.5 (<< 5.5.33)
-Replaces: libmariadbclient18
-Provides: libmariadbclient18, default-libmysqlclient-dev, libmariadbclient-dev-compat
+Replaces: libmariadbclient18, libmysqlclient18, libmysqlclient19, libmysqlclient20
+Provides: libmariadbclient18, libmysqlclient18, libmysqlclient19, libmysqlclient20
 Description: MariaDB database client library
  MariaDB is a fast, stable and true multi-user, multi-threaded SQL database
  server. SQL (Structured Query Language) is the most popular database query
@@ -60,7 +60,6 @@ Package: libmysqlclient18
 Section: libs
 Architecture: any
 Depends: libmariadb3 (= ${binary:Version}), ${misc:Depends}
-Replaces: libmysqlclient18 (<< ${source:Version})
 Description: Virtual package to satisfy external depends
  This is an empty package that depends on the libmariadb3
  package.

debian/libmariadb3.install

 usr/lib/mariadb/libmariadb.so.*
 usr/lib/*/libmariadbclient.so.*
+usr/lib/*/libmysqlclient.so.*
 usr/lib/mysql/plugin/dialog.so
 usr/lib/mysql/plugin/mysql_clear_password.so

debian/rules

@@ -160,6 +160,11 @@ override_dh_auto_install:
 	# Install libmariadbclient18 compatibility links
 	ln -s /usr/lib/mariadb/libmariadb.so.3 $(TMP)/usr/lib/$(DEB_HOST_MULTIARCH)/libmariadbclient.so.18
 
+	# Install libmysqlclientclientXX compatibility links
+	ln -s /usr/lib/mariadb/libmariadb.so.3 $(TMP)/usr/lib/$(DEB_HOST_MULTIARCH)/libmysqlclient.so.18
+	ln -s /usr/lib/mariadb/libmariadb.so.3 $(TMP)/usr/lib/$(DEB_HOST_MULTIARCH)/libmysqlclient.so.19
+	ln -s /usr/lib/mariadb/libmariadb.so.3 $(TMP)/usr/lib/$(DEB_HOST_MULTIARCH)/libmysqlclient.so.20
+
 	touch $@
 
 override_dh_installlogrotate-arch: