mariadb: make it be able to work with SELinux

1. change the datadir from /var/mysql to /var/lib/mysql
2. after creating datedir, restorecon on it, make SELinux be able to
work
3. Add the PIDFile for systemd unit file, otherwise systemctl can not
stop mysqld

Signed-off-by: Roy Li <rongqing.li@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-oe/recipes-support/mysql/mariadb.inc

@@ -128,6 +128,7 @@ pkg_postinst_${PN}-server () {
 
     mysql_install_db --basedir=${prefix} --user=mysql
 
+    [ -x /sbin/restorecon ] && /sbin/restorecon -RF /var/lib/mysql
 }
 
 PACKAGES = "${PN}-dbg ${PN} \

meta-oe/recipes-support/mysql/mariadb/my.cnf

@@ -13,7 +13,7 @@ socket 						= /var/lib/mysql/mysql.sock
 pid-file 					= /var/lib/mysql/mysqld.pid
 log-error 					= /var/log/mysqld.err
 basedir 					= /usr
-datadir 					= /var/mysql
+datadir 					= /var/lib/mysql
 skip-external-locking
 skip-networking
 ignore-builtin-innodb

meta-oe/recipes-support/mysql/mariadb/mysqld.service

@@ -4,6 +4,7 @@ After=syslog.target
 After=network.target
 
 [Service]
+PIDFile=/var/lib/mysql/mysqld.pid
 Type=simple
 User=mysql
 Group=mysql