MDEV-13836 mariadb_config & mysql_config output differ

allow to build with the default port number 3306.
Now -DMYSQL_TCP_PORT=# sets the default port name and
-DMYSQL_TCP_PORT_DEFAULT=# sets the magic port=0 behavior,
if it's MYSQL_TCP_PORT_DEFAULT=0 it's enabled, otherwise - disabled.

cmake/mysql_version.cmake

@@ -69,13 +69,9 @@ ENDMACRO()
 # Get mysql version and other interesting variables
 GET_MYSQL_VERSION()
 
-SET(MYSQL_TCP_PORT_DEFAULT "3306")
-
+SET(MYSQL_TCP_PORT_DEFAULT 0)
 IF(NOT MYSQL_TCP_PORT)
-  SET(MYSQL_TCP_PORT ${MYSQL_TCP_PORT_DEFAULT})
-  SET(MYSQL_TCP_PORT_DEFAULT "0")
-ELSEIF(MYSQL_TCP_PORT EQUAL MYSQL_TCP_PORT_DEFAULT)
-  SET(MYSQL_TCP_PORT_DEFAULT "0")
+  SET(MYSQL_TCP_PORT 3306)
 ENDIF()
 
 IF(NOT COMPILATION_COMMENT)