gcc conformance to HP-PA ABI

[Richard Kenner]

    Better to hack it in the direction we'd like to go (dwarf2 unwinders)
    than in a direction we do not want to go (compatible with HP's
    unwinder library).

Why is that a direction we don't want to go?  Isn't it always better for GC
to be compatible with as many vendor features as possible?  Shouldn't we be
able to mix vendor- and GCC-built object files when processing exceptions?

What about linking with third-party libraries and propagating exceptions
through them?  Wouldn't that be simpler if using HP's unwinder library?