Print system info before testing

[junaruga]

Print a system info to make debugging easy before testing if RUBY_MYSQL2_DEBUG == true.

What I want.

Client info

+      puts "Client info: #{Mysql2::Client.info}"
+      puts "Client encoding: #{client.encoding}"

Client info: {:id=>100505, :version=>"10.5.5", :header_version=>"10.5.5"}
Client encoding: UTF-8

Client msyql2.so library's dependency paths.

Find a Ruby bindings gem of ldd to implement it to just use it to print the info in the process of the rake spec.
It's not a good time to add a new feature to mysql2, as we want to focus fixing the test failures on CI an drelesae next maintenance version.

Server info

+      puts "Server info: #{client.server_info}

Server info: {:id=>100509, :version=>"10.5.9-MariaDB-1:10.5.9+maria~focal"}

Used variables in the spec files.

mysql -u "mockbuild" -S test_db/mysql.sock -e "SHOW VARIABLES WHERE Variable_name IN ('have_ssl', 'local_infile', 'performance_schema');"
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| have_ssl           | YES   |
| local_infile       | ON    |
| performance_schema | OFF   |
+--------------------+-------+

{"Variable_name"=>"have_ssl", "Value"=>"YES"}
{"Variable_name"=>"local_infile", "Value"=>"ON"}
{"Variable_name"=>"performance_schema", "Value"=>"ON"}