builtins.c (expand_builtin_pow, [...]): Remove uses of dconst3, dconstsqrt2, dconstthird, dconste and/or dconst10.

	* builtins.c (expand_builtin_pow, fold_builtin_cabs,
	fold_builtin_sqrt, fold_builtin_cbrt, fold_builtin_logarithm,
	fold_builtin_hypot, fold_builtin_pow): Remove uses of dconst3,
	dconstsqrt2, dconstthird, dconste and/or dconst10.
	* config/i386/i386.c (ix86_emit_swsqrtsf): Likewise.
	* emit-rtl.c (dconst3, dconst10, dconstm2, dconstthird,
	dconstsqrt2, dconste): Delete.
	(init_emit_once): Likewise.  Simplify initializing dconstm1.
	Constify variable.
	* real.c (get_real_const): New.
	* real.h (dconst3, dconst10, dconstm2, dconstthird,
	dconstsqrt2, dconste): Delete.
	(real_value_const, get_real_const): New.

From-SVN: r133607