prefer in-tree libiconv over the system libiconv?

[Joel Brobecker <brobecker@adacore.com>]

Hello everyone,

Tom and I were discussing about libiconv today: The idea is that,
if you put the libiconv sources in the root directory of the GDB
sources, configure will automatically pick it up and build GDB
with this libiconv. However, the current setup is such that, if
we find a system libiconv that provides the functionality we need,
then the system libiconv is going to be used instead.

This means that placing the libiconv sources in the GDB sources
is not enough to make sure that GDB gets built with that libiconv.

On the one hand, this is convenient if you just want GDB to be built
without having to worry whether libiconv is available on the host
or not.

But, on the other hand, for a distributer like AdaCore (and maybe CS),
it makes it harder to make sure which libiconv gets linked in.
I suggest we change the logic a bit so that, if the libiconv sources
are in-tree, then use this libiconv over the system one.  The
alternative is to have a configure switch that would allow us to
specify the location of the libiconv install from the in-tree build.

Thoughts?

-- 
Joel