ngcp-services metapackage: support mysql + percona packages at the same time

Since our current Jenkins trigger default to builds against
squeeze currently we get packages that are meant for Debian/wheezy
also built against squeeze and therefore ending up in Debian/squeeze.
To address that until we made the full switch over to Debian/wheezy
as default build target we need to support squeeze + wheezy at
the same time.

Addressing:

| The following packages have unmet dependencies:
|  mysql-client-5.1 : Depends: libmysqlclient16 (>= 5.1.66-0+squeeze1) but 5.1.57-rel12.8-233.squeeze is to be installed

from http://paste.mgm.sipwise.com/show/333/

From: Michael Prokop <mprokop@sipwise.com>

debian/control

@@ -143,8 +143,8 @@ Depends: bsd-mailx | mailx,
          linux-headers-3.2.0-0.bpo.4-amd64 | linux-headers-3.2.0-4-all,
          linux-image-3.2.0-0.bpo.4-amd64 | linux-image-3.2.0-4-amd64,
          monit,
-         mysql-client,
-         mysql-server,
+         mysql-client | percona-server-client-5.1,
+         mysql-server | percona-server-server-5.1,
          ngcp-asterisk,
          ngcp-cdr-exporter,
          ngcp-check-tools,
@@ -198,8 +198,8 @@ Depends: bsd-mailx | mailx,
          kamailio-xml-modules,
          linux-headers-3.2.0-0.bpo.4-amd64 | linux-headers-3.2.0-4-all,
          linux-image-3.2.0-0.bpo.4-amd64 | linux-image-3.2.0-4-amd64,
-         mysql-client,
-         mysql-server,
+         mysql-client | percona-server-client-5.1,
+         mysql-server | percona-server-server-5.1,
          ngcp-asterisk,
          ngcp-cdr-exporter,
          ngcp-check-tools,
@@ -248,8 +248,8 @@ Depends: bsd-mailx | mailx,
          kamailio-tls-modules,
          kamailio-utils-modules,
          kamailio-xml-modules,
-         mysql-client,
-         mysql-server,
+         mysql-client | percona-server-client-5.1,
+         mysql-server | percona-server-server-5.1,
          ngcp-asterisk,
          ngcp-cdr-exporter,
          ngcp-check-tools,