PATCH multi-arch GET_LONGJMP_TARGET

[Richard Earnshaw]

> 
> This patch makes that
> GET_LONGJMP_TARGET is always defined for all mutiarched target
> (even partial !).
> 
> Thus it breaks compilation of Cygwin native GDB,
> because JB_PC and JB_ELEMENT_SIZE are not defined for these targets.
> (and several other i386 targets)
> 
> The correct fix would be to add these values to gdbarch ...
> 
> The following was committed as an obvious fix.

Ah, sorry about that.

Perhaps it would also be sensible to check GET_LONGJMP_TARGET_P() in that 
code and always return 0 if it is false.

I'll go around the other tdep files and clean those up as well.

R.