Warning about zero-sized dynamic symbols

[Ian Lance Taylor]

Alan, back in http://sourceware.org/ml/binutils/2005-08/msg00279.html
you added an error to GNU ld about dynamic variables that have a zero
size.  The Go language permits global variables to have a zero size, and
that is even useful as a way of aggregating methods (e.g., in the
encoding/binary package in Go's standard library the variables BigEndian
and LittleEndian have a zero size).  I've worked around the problem in
the gccgo compiler, but thinking about it I don't think the error is
appropriate.

Ian