alpha: Fix soft-fp breakage

Commit 5c0508a318af0a6c8be2a4cb2e3b76896218bf35 broke the Alpha
port, as the extra parenthesis got in the way of some token pasting
that we were doing in a redefined raw unpack macro.

Avoid this situation in the future by not attempting to redefine a
basic macro, but rather work from the outermost public interface.
The compiler does in fact see through the added indirection.

	* sysdeps/alpha/soft-fp/local-soft-fp.h (_FP_UNPACK_RAW_2): Remove.
	(_FP_PACK_RAW_2): Remove.
	(AXP_DECL_RETURN_Q): Rename from FP_DECL_RETURN, use _FP_UNION_Q.
	(AXP_RETURN_Q): Rename from FP_RETURN, use _FP_UNION_Q.
	(AXP_UNPACK_RAW_Q, AXP_UNPACK_SEMIRAW_Q, AXP_UNPACK_Q): New.
	(AXP_PACK_RAW_Q, AXP_PACK_SEMIRAW_Q, AXP_PACK_Q): New.
	* sysdeps/alpha/soft-fp/ots_add.c (_OtsAddX): Update to match.
	* sysdeps/alpha/soft-fp/ots_cmp.c (internal_equality): Likewise.
	* sysdeps/alpha/soft-fp/ots_cmpe.c (internal_compare): Likewise.
	* sysdeps/alpha/soft-fp/ots_cvtqux.c (_OtsCvtQUX): Likewise.
	* sysdeps/alpha/soft-fp/ots_cvtqx.c (_OtsCvtQX): Likewise.
	* sysdeps/alpha/soft-fp/ots_cvttx.c (_OtsConvertFloatTX): Likewise.
	* sysdeps/alpha/soft-fp/ots_cvtxq.c (_OtsCvtXQ): Likewise.
	* sysdeps/alpha/soft-fp/ots_cvtxt.c (_OtsConvertFloatXT): Likewise.
	* sysdeps/alpha/soft-fp/ots_div.c (_OtsDivX): Likewise.
	* sysdeps/alpha/soft-fp/ots_mul.c (_OtsMulX): Likewise.
	* sysdeps/alpha/soft-fp/ots_nintxq.c (_OtsNintXQ): Likewise.
	* sysdeps/alpha/soft-fp/ots_sub.c (_OtsSubX): Likewise.