Use libm_alias_ldouble in sysdeps/x86_64/fpu.

This patch continues the preparation for additional _FloatN / _FloatNx
function aliases by using libm_alias_ldouble for sysdeps/x86_64/fpu
long double functions, so that they can have _Float64x aliases added
in future.

Tested for x86_64, including build-many-glibcs.py tests that installed
stripped shared libraries are unchanged by the patch.

	* sysdeps/x86_64/fpu/e_expl.S: Include <libm-alias-ldouble.h>.
	[USE_AS_EXPM1L] (expm1l): Define using libm_alias_ldouble.
	* sysdeps/x86_64/fpu/s_ceill.S: Include <libm-alias-ldouble.h>.
	(ceill): Define using libm_alias_ldouble.
	* sysdeps/x86_64/fpu/s_copysignl.S: Include
	<libm-alias-ldouble.h>.
	(copysignl): Define using libm_alias_ldouble.
	* sysdeps/x86_64/fpu/s_fabsl.S: Include <libm-alias-ldouble.h>.
	(fabsl): Define using libm_alias_ldouble.
	* sysdeps/x86_64/fpu/s_floorl.S: Include <libm-alias-ldouble.h>.
	(floorl): Define using libm_alias_ldouble.
	* sysdeps/x86_64/fpu/s_fmaxl.S: Include <libm-alias-ldouble.h>.
	(fmaxl): Define using libm_alias_ldouble.
	* sysdeps/x86_64/fpu/s_fminl.S: Include <libm-alias-ldouble.h>.
	(fminl): Define using libm_alias_ldouble.
	* sysdeps/x86_64/fpu/s_llrintl.S: Include <libm-alias-ldouble.h>.
	(llrintl): Define using libm_alias_ldouble.
	(lrintl): Likewise.
	* sysdeps/x86_64/fpu/s_nearbyintl.S: Include
	<libm-alias-ldouble.h>.
	(nearbyintl): Define using libm_alias_ldouble.
	* sysdeps/x86_64/fpu/s_truncl.S: Include <libm-alias-ldouble.h>.
	(truncl): Define using libm_alias_ldouble.
	* sysdeps/x86_64/x32/fpu/s_lrintl.S: Include
	<libm-alias-ldouble.h>.
	(lrintl): Define using libm_alias_ldouble.