PHP Memory is not correctly identified when value is not in megabytes

[ddb4github]

Describe the bug
Installation Wizard can not identify PHP-->memory_limit when unit is not 'M'

To Reproduce
Steps to reproduce the behavior:

1. Prepare Cacti 1.2.7 or earlier env
2. Edit /etc/php.ini, set memory_limit = 2G
3. Restart httpd service
4. Web access Cacti and Click Next
5. See error

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
set memory_limit to 2G in php.ini

set memory_limit to 2048M in php.ini

[netniV]

Good catch. I'll see if I can fix this one up unless you already have a patch for it?