Adding FGL to the hierarchical libraries

[Keith Wansbrough]

> Don't name the intermediate directories (subheirarchies) or modules Aux.
> On Windows platforms (at least 2k, almost certainly earlier ones as well
> though) aux (or aux.* in general) is a special file name. 

Certainly since MSDOS 2.0, possibly even 1.0.

IIRC, the reserved names include aux:, con:, prn:, com1:, com2:,
com3:, com4:, lpt1:, lpt2:, lpt3:, and nul:.  The syntax with the
trailing colon is official, but not necessary.  So don't name anything
with these names :-(

--KW 8-)