[PATCH 15/16][fold-const.c] Fix bigendian HFmode in native_interpret_real

[Alan Lawrence]

Richard Biener wrote:
>
> I wonder why wi::from_buffer doesn't have the same issue though
> for HImode ints.  It's structured differently, without magic '4's as well.

I don't claim to understand the rest of wi::from_buffer and why it is different. 
However, wrt. HImode, I think the key line is:

  offset = BYTES_BIG_ENDIAN ? (buffer_len - 1) - byte : byte;

HTH,
Alan