Fix bogus error on Value_Size clause for variant record type

This is a regression present on the mainline and 10 branch: the compiler
rejects a Value_Size clause on a discriminated record type with variant.

gcc/ada/ChangeLog:
	* gcc-interface/decl.c (set_rm_size): Do not take into account the
	Value_Size clause if it is not for the entity itself.

gcc/testsuite/ChangeLog:
	* gnat.dg/specs/size_clause5.ads: New test.

1 files changed, 16 insertions, 0 deletions

diff --git a/gcc/testsuite/gnat.dg/specs/size_clause5.ads b/gcc/testsuite/gnat.dg/specs/size_clause5.ads
new file mode 100644
index 0000000..ba45bbf
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/specs/size_clause5.ads
@@ -0,0 +1,16 @@
+-- { dg-do compile }
+
+package Size_Clause5 is
+
+  type Arr is array (1 .. 16) of Boolean;
+
+  type RRec (D : Boolean) is record
+    case D is
+      when True =>  I : Integer;
+      when False => A : Arr;
+    end case;
+  end record;
+  for RRec'Object_Size use 160;
+  for RRec'Value_Size use 160;
+
+end Size_Clause5;