Add RI stub

tests/testsuite/test-via/challenge_ri.ada

+--  Stub generated by OpenGEODE.
+--  You can edit this file, it will not be overwritten
+
+package body challenge_RI is
+   procedure pow (a : in out asn1SccT_UInt32; b : in out asn1SccT_UInt32; res : out asn1SccT_UInt32) is 
+       procedure pow (a : in out asn1SccT_UInt32; b : in out asn1SccT_UInt32; res : out asn1SccT_UInt32) with Import, Convention => C, Link_Name => "challenge_RI_pow";
+   begin
+       Pow (a, b, res);
+   end Pow;
+
+end challenge_RI;