[Clfs-support] Flex not found config error on CLFS 7.12 boot method

[Andrew Reyes]

Ok I think I found something. I found that by installing flex on the 
host system it configures fine. Thinking maybe we should update the 
'Host System Requirements' section of the book and add flex as part of 
the requirements. If I'm wrong please let me know as I'm learning as I 
go and trying to help for future CLFS builders.