WL#5608: Assert that all distributed files follow the principle of most restrictive permission possible

Executive Summary
-----------------

Files generated by the application should be given the most restrictive file
permissions possible. Please perform a review of the file permissions on
different platforms, focusing particularly on password files, audit or log files
and configuration files. This review might need to have a short-term and a
medium term aspect. In the short term tighten up permission as much as possible
without breaking anything. In the medium term look to change scripts and code
that depend on permissive file permissions, to allow further tightening of
permissions.

What We Have
------------

Running mysql_install_db generates number of files under data directory. These
files include:

    Directories for various databases
    Files corresponding to various tables in each database
    Log files
    Configuration file 

Apart from this, installation also generates default configuration file (my.cnf)
and some other files (e.g. audit log if audit plugin is used). 

User/Group Permission

F1 : data directory should have drwxr-x--- permission with respect to mysql/mysql.

I1 : Change default directory permission from 0700 to 0770. This will allow
default "mysql" group to access data directory and its sub directory.

I2 : Change mysql_install_db to create data directory with permission drwxrwx---
with respect to effective user and its primary group(--user parameter).