* real.h: Define REAL_VALUE_TYPE_SIZE as 96 or 160, as
	appropriate.  Document need for extended precision even when
	MAX_LONG_DOUBLE_TYPE_SIZE is smaller.  Define REAL_WIDTH here,
	based on REAL_VALUE_TYPE_SIZE.  Use REAL_WIDTH to size
	REAL_VALUE_TYPE.  Define CONST_DOUBLE_FORMAT here.  Use #error
	instead of relying on later syntax error when REAL_WIDTH > 5.
	* real.c: Define NE based only on whether or not we have a
	full 128-bit extended type (not INTEL_EXTENDED_IEEE_FORMAT).
	Require sizeof(REAL_VALUE_TYPE) == 2*NE.  Unconditionally
	define GET_REAL and PUT_REAL as simple memcpy operations; no
	need to byteswap or round.
	Use #error instead of #ifdef-ing out the entire file, for
	prompt error detection.

	* rtl.c, gengenrtl.c: No need to calculate CONST_DOUBLE_FORMAT here.

From-SVN: r52502