Erratic ftello() without _LARGEFILE_SOURCE

[Reynir Stefansson]

On some systems (mine included), ftello() sneezes nasal demons when 
_FILE_OFFSET_BITS is defined as 64 and _LARGEFILE_SOURCE is not defined. 
A site config file helps, but I doubt it's an ideal solution.

Reynir H. Stefánsson (address@hidden)
--
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