[libstdc++] Use LD_RUN_PATH when linking abi_check

[Phil Edwards]

> > > Speaking of LD_LIBRARY64_PATH: make check-abi currently doesn't cater for
> > > multilibbed systems like Solaris 8 and IRIX 6.  I suggest placing
> > > baseline_symbols.txt in the corresponding subdirs of config/abi (like
> > > sparc-sun-solaris2.8/sparcv9 and mips-sgi-irix6.5/mabi=64) and running
> > > abi_check for every multilib.  I'm low on time for gcc hacking lately, so I
> > > haven't yet figured out how to do so.
> > 
> > Running for each multilib is a good idea, although I'd prefer not to have
> > more nested subdirectories, with one file in each dir.  I'll add this to
> > the todo list.
> 
> Um. Isn't 'make check-abi' only useful for systems that are actually
> using versioning, like BSD and Linux? I'm not aware of other platforms
> that actually are using symbol versioning. 
> 
> Perhaps it is useful, but that was not the intention of this Makefile
> rule.
> 
> Must be missing something,

Solaris?  It's not currently doing versioning, but it could with some
legwork.  More, I'm sure that someday not too far away it /will/ do
versioning, and then we'll have to support multilibs in check-abi anyhow.

The most recent patch I posted would IMHO be a good first step, when we
need that to happen.  Until then, I'm content with letting it stay in the
archives as an example.


Phil

-- 
I would therefore like to posit that computing's central challenge, viz. "How
not to make a mess of it," has /not/ been met.
                                                 - Edsger Dijkstra, 1930-2002