[libunwind] makefile rewrite

[Richard Henderson]

I couldn't make automake do what I wanted; it simply doesn't have
any reasonable amount of pattern-matching ability.  So I rewrote
all of it to use gnu make instead.

After cutting out automake, libtool started misbehaving and no
longer would create shared libraries.  There didn't appear to be
any difference in the command line, or the built libtool script.
I eventually tired of fighting with this write-only script and cut
it out of the loop as well.  For linux, -fpic and -shared are
sufficient.

A patch for this is quite large.  Instead, I've put up a mercurial
repository with the changes in; one can pull and compare easily.

  http://are.twiddle.net:8000/

Comments appreciated.


r~