glibc ABI symbol list checking

[Roland McGrath]

> Hi Roland, this is really a good idea!

It's a start, but I don't want to let it make us complacent.  It's far from
a complete solution.  Something that keeps track of the type signatures
would make a bigger difference.

> But the makefile hacks seems not to be complete, I get (both with
> check-abi and update-abi) a failure in the locale directory: 

Sorry if I wasn't clear about this.  They won't work until some reference
files are installed, subdir/libfoo.abilist for each libfoo.so we build.  
So start by touch locale/libBrokenLocale.abilist et al, and then check-abi
should show you diffs containing the whole .symlist with +s, and update-abi
will work.  

I had intended to get some initial reference lists in shortly after my
first posting, but I've been sick this week.

> For which platforms will you do the lists yourself - and for which do
> you need help?

Not sure yet.