(e64toe): Properly distinguish between NaN and infinity bit patterns for real-words-big-endian targets.

(e64toe): Properly distinguish between NaN and infinity bit patterns
for real-words-big-endian targets.
(endian): Add two explicit casts.
(e64toe): Support ARM extended precision fp format.  Check negative
infinities properly for NaNs.
(toe64): Support ARM extended precision fp format.

From-SVN: r11688