Document empty structures

[Joseph S. Myers]

On Fri, 11 Apr 2003, Geoffrey Keating wrote:

> This adds documentation of GCC's empty structure extension.

I think there needs to be something about how empty structures interact
with initializer lists (when initializing a structure which has as an
element an empty structure): do lists of scalars ignore the empty
structure, does { } explicitly initialize it, ...?

-- 
Joseph S. Myers
jsm28@cam.ac.uk