Introduce support for location views

[Nick Clifton]

Hi Alex,

> Here's a consolidated patch that combines the original patch with all of
> the incremental changes posted so far (minus the riscv patchlets), and
> one extra patch that moves the leb128 operand-is-defined check to a IMHO
> more suitable place.
 
  Thanks - I have applied your patch.

  I made a couple of small changes:

  * There were a few places in some the new gas tests where you were using
  the .int pseudo-op and expecting it to insert 4-bytes.  This is not true
  of all targets, as some have 2-byte or even 8-byte integers.  I replaced
  the .int occurences with .dc.l instead which achieves the desired purpose.

  * I add a line to the gas/NEWS file mentioning this new feature.

  * I added target specific skip directives to the new tests, along with
  comments explaining why each target was skipped.


Cheers
  Nick