[Ada] PR ada/98724: Alpha/Linux/libada: Use wraplf for Aux_Long_Long_Float

Use the Long Long Float wrapper in terms of Long Float for Alpha/Linux
targets as well, fixing gnatlib compilation errors:

a-nallfl.ads:48:13: warning: intrinsic binding type mismatch on result [enabledby default]
a-nallfl.ads:48:13: warning: intrinsic binding type mismatch on parameter 1 [enabled by default]
a-nallfl.ads:48:13: warning: profile of "Sin" doesn't match the builtin it binds [enabled by default]

etc. with the `alpha-linux-gnu' target.

	gcc/ada/
	PR ada/98724
	PR ada/97504
	* Makefile.rtl (LIBGNAT_TARGET_PAIRS) <alpha*-*-linux*>: Use
	wraplf version of Aux_Long_Long_Float.