[hpux] Improve handling of unwind records for hp compiler

[Randolph Chung]

Randolph Chung wrote:
> As discussed recently on the gdb mailing list, current gdb has problems
> unwinding code generated by the HP compiler. The attached patch teaches
> the hppa unwinder about two additional flags in the unwind record
> generated by the HP toolchain.
> 
> For some reason in the gdb code, the "alloca_frame" bit is called
> Pseudo_SP_Set; most HP docs refer to it as alloca_frame. I'll submit a
> separate change to improve the "maint print unwind" command to print out
> all the unwind record flags and change the name of the alloca_frame flag
> to match the documentation.
> 
> This patch was tested with no regressions against GNU tools on
> hppa2.0w-hp-hpux11.11 and hppa64-hp-hpux11.11. I only tested it against
> one HP compiled program I have on hand (wdb).
> 
> I'll commit this in a couple of days if there are no additional comments.

3 months late, but this is committed now.

randolph