Fix MySQL-python build on Centos

The build of MySQL-python started to fail after the update to
Percona-Server-devel-56-5.6.27-rel76.0.el7.x86_64 with:

  /usr/bin/ld: cannot find -lmysqlclient

It appears Percona-Server-devel package provides a broken
/usr/lib64/libmysqlclient.so that points to nonexistent
libmysqlclient.so.18.

Fix the build by installing MariaDB-shared package from the mariadb
repo that contains the missing file.

Change-Id: Ia95fddfe44f54bd355c6f3d0ac895fdc05cecff9
Closes-Bug: #1526129

docker/kolla-ansible/Dockerfile.j2

@@ -3,6 +3,7 @@ MAINTAINER {{ maintainer }}
 
 {% if base_distro in ['centos', 'fedora', 'oraclelinux', 'rhel'] %}
 
+# TODO(mandre) remove MariaDB-shared once Percona has fixed its packaging issue
 RUN yum -y install \
         gcc \
         git \
@@ -11,6 +12,7 @@ RUN yum -y install \
         libxslt-devel \
         mariadb-devel \
         mariadb-libs \
+        MariaDB-shared \
         openssl-devel \
         python-devel \
         openssh-clients \

docker/openstack-base/Dockerfile.j2

@@ -2,11 +2,12 @@ FROM {{ namespace }}/{{ image_prefix }}base:{{ tag }}
 MAINTAINER {{ maintainer }}
 
 {% if base_distro in ['fedora', 'centos', 'oraclelinux', 'rhel'] %}
+# TODO(mandre) remove MariaDB-shared once Percona has fixed its packaging issue
 RUN yum -y install \
         git \
         iproute \
         mariadb-libs \
-        MySQL-python \
+        MariaDB-shared \
         openssl \
     && yum clean all
 {% endif %}