Add a test for library-level generic instantiations.

Author: tjj2017

testsuite/gnat2goto/tests/do_not_generate_json_for_generic_bodies/gen_pack.adb

@@ -0,0 +1,12 @@
+package body Gen_Pack is
+
+   -------
+   -- G --
+   -------
+
+   function G (V : T) return T is
+   begin
+      return V;
+   end G;
+
+end Gen_Pack;

testsuite/gnat2goto/tests/do_not_generate_json_for_generic_bodies/gen_pack.ads

@@ -0,0 +1,5 @@
+generic
+   type T is (<>);
+package Gen_Pack is
+   function G (V : T) return T;
+end Gen_Pack;

testsuite/gnat2goto/tests/do_not_generate_json_for_generic_bodies/main.adb

@@ -0,0 +1,6 @@
+with My_Pack;
+procedure Main is
+   I : Integer := 3;
+begin
+   pragma Assert (My_Pack.G (I) = 3);
+end Main;

testsuite/gnat2goto/tests/do_not_generate_json_for_generic_bodies/my_pack.ads

@@ -0,0 +1,3 @@
+with Gen_Pack;
+--  Test library-level generic instantiation.
+package My_Pack is new Gen_Pack (Integer);

testsuite/gnat2goto/tests/do_not_generate_json_for_generic_bodies/test.out

@@ -0,0 +1,2 @@
+[main.assertion.1] line 5 assertion My_Pack.G (I) = 3: SUCCESS
+VERIFICATION SUCCESSFUL

testsuite/gnat2goto/tests/do_not_generate_json_for_generic_bodies/test.py

@@ -0,0 +1,3 @@
+from test_support import *
+
+prove(main='main.adb', specs=['my_pack.ads'])