Correctly type sctp_assoc_id as signed, not unsigned

The underlying type of an SCTP association ID is a signed 32-bit
integer on common platforms (Solaris, Linux & Mac OS/X NKE).
The SCTP socket API draft spec (draft-ietf-tsvwg-sctpsocket-19)
defines only one special value, zero.

Although particular platform implementations may impose other
restrictions, the type check in prim_inet should allow all valid values.

erts/preloaded/src/prim_inet.erl

@@ -1340,7 +1340,7 @@ type_value_2(binary_or_uint,Bin) when is_binary(Bin) -> true;
 type_value_2(binary_or_uint,Int) when is_integer(Int), Int >= 0 -> true;
 %% Type-checking of SCTP options
 type_value_2(sctp_assoc_id, X)
-  when X band 16#ffffffff =:= X                     -> true;
+  when is_integer(X), X >= -2147483648, X =< 2147483647 -> true;
 type_value_2(_, _)         -> false.