Fix stack backtraces on 26-bit ARM

[Andrew Cagney]

> I'm trying to make GDB 5.0 work on NetBSD/arm26.  One problem I've run
> into is that even with "set apcs32 0", stack backtraces include flags in
> the program counter for all frames apart from the top one.  I think this
> patch fixes the problem by using arm_addr_bits_remove() to clean up the
> PC fetched from a stack frame.  I'm not in a position to check this still
> works on arm32 and thumb.

Hmm, this could get interesting.  A NetBSD/arm port of GDB would 
certainly help improve the quality of the Arm GDB target.  Your 
contribution are going to be most welcome.  Problem is, I can't find a 
copyright assignment for you (you'll get a separate e-mail about this). 
  Can you please clarify your assignment status?  Not having an 
assignment can make things, er, interesting.  At present your submitting 
small simple bugs that can be described in simple english.

The other thing to know is that patches should be against the current 
trunk rather than the last release.  5.0 is just so old ...

Anyway I'm sure you'll be hearing from the relevant target maintainers soon.

enjoy,
Andrew