cdr_mysql: Compile error because MYSQL_PORT definition is missing

If it is not defined, it will add MYSQL_PORT definition. After some
research on MySQL/MariaDB development tree, I couldn't find any reference
to MYSQL_PORT definition in include files.

ASTERISK-27782 #close

Change-Id: Ieee56c836fc2e8bd021c456145bba04c6068bb77

addons/cdr_mysql.c

@@ -58,6 +58,14 @@
 
 #define DATE_FORMAT "%Y-%m-%d %T"
 
+#ifndef MYSQL_PORT
+# ifdef MARIADB_PORT
+#  define MYSQL_PORT MARIADB_PORT
+# else
+#  define MYSQL_PORT 3306
+# endif
+#endif
+
 AST_THREADSTORAGE(sql1_buf);
 AST_THREADSTORAGE(sql2_buf);
 AST_THREADSTORAGE(escape_buf);