Issue #1678380: When distinguishing between -0.0 and 0.0 in compiler_add_o, use copysign instead of examining the first and last bytes of the double.  The latter method fails for little-endian ARM, OABI, where doubles are little-endian but with the words swapped.
Issue #1678380: When distinguishing between -0.0 and 0.0 in
compiler_add_o, use copysign instead of examining the first and last
bytes of the double.  The latter method fails for little-endian
ARM, OABI, where doubles are little-endian but with the words swapped.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator