Thin archive relative directory calculation

[Andrew Baxter]

I'm getting some incorrect directories in my thin .a files when creating 
the library in a directory above the current one.  For example, if I do 
"ar rT ../x.a x.o" from the directory y, the relative location of x.o as 
specified in x.a is "../x.o" and not "y/x.o".  It doesn't seem to be a 
problem in the opposite direction -- "ar rT x.a y/x.o" generates the 
relative location as "y/x.o".

Actually, is this a bug?  I couldn't find any examples of the thin 
archives being used googling after around for a while, so I'm not sure 
my usage is correct.

Also, when using the broken .a files, ar t, ld, nm, and objdump give not 
particularly useful error messages and produce no output.  For instance, 
ar t produces: "ar: x.a: No such file or directory".

I'm using version 2.21.0.20110209.  I have a zipped up test case, but it 
would probably take more time to extract it than to write your own.  I'd 
be glad to send it if it would be useful.

Cheers,
Andrew Baxter