[Ada] Fix an ICE on instantiated subprogram with -gnatc

The following should compile quietly:

$ gcc -c p-proc.ads -gnatc

procedure P.Proc is new G;

with Q;

package P is

  generic procedure G;

end P;

with System;
with Unchecked_Conversion;

package Q is

  generic package Inner_G is

    type T is access all Integer;

    function Cnv is new Unchecked_Conversion (System.Address, T);

  end Inner_G;

end Q;

2018-12-11  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* gcc-interface/trans.c (elaborate_all_entities_for_package):
	Skip aliasing subprograms.

From-SVN: r266984

gcc/ada/ChangeLog

+2018-12-11  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gcc-interface/trans.c (elaborate_all_entities_for_package):
+	Skip aliasing subprograms.
+
 2018-12-11  Bob Duff  <duff@adacore.com>
 
 	* doc/gnat_ugn/gnat_utility_programs.rst: Update gnatmetric

gcc/ada/gcc-interface/trans.c

@@ -9278,7 +9278,9 @@ elaborate_all_entities_for_package (Entity_Id gnat_package)
 	continue;
       if (kind == E_Operator)
 	continue;
-      if (IN (kind, Subprogram_Kind) && Is_Intrinsic_Subprogram (gnat_entity))
+      if (IN (kind, Subprogram_Kind)
+	  && (Present (Alias (gnat_entity))
+	      || Is_Intrinsic_Subprogram (gnat_entity)))
 	continue;
       if (Is_Itype (gnat_entity))
 	continue;