re PR other/37897 (decNumber functions break strict-aliasing rules)

re PR other/37897 (decNumber functions break strict-aliasing rules)

	PR other/37897
	* decDouble.h (decDouble): Replace struct with union accessible
	by more types.
	* decSingle.h (decSingle): Ditto.
	* decQuad.h (decQuad): Ditto.
	* decNumberLocal.h (DFWORD, DFBYTE, DFWWORD): access decFloat via
	new members.
	* decBasic.c (decFloatCompareTotal): Avoid type-pun violation.
	(decNumberCompare): Ditto.

From-SVN: r141386