[patch] Bring QNX Neutrino support forward.

[Andrew Cagney]

> Some of this stuff is cosmetic/convenience.  I made the macros for my nto_target structure testable and moved the comments into the structure where they're more useful.
> 
> A few things had to do with initializers.  Some of the signal handling stuff didn't work because other _init functions hadn't been called so I moved them out to where they could be called when the osabi is initialized.

BTW, what was the race condition?

> I added osabi and core sniffers.  Some is practical, some is future-proofing.  If we start supporting multiple targets, I'm going to want to be able to swap our various target processors support in and out.  The is_nto_target type stuff can be made more interesting later to do things like check to see if the remote host processor matches the binary abi and such.

You should also be able to kill off regset_core_fns, it's been 
superseeded by regsets (which reminds me ....).

Andrew