[Ada] Bug fix in "=" function of formal doubly linked list

[Pierre-Marie de Rodat via Gcc-patches]

Correction of a typo regarding indexes.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * libgnat/a-cfdlli.adb ("="): Make the function properly loop
        over the right list.
diff --git a/gcc/ada/libgnat/a-cfdlli.adb b/gcc/ada/libgnat/a-cfdlli.adb
--- a/gcc/ada/libgnat/a-cfdlli.adb
+++ b/gcc/ada/libgnat/a-cfdlli.adb
@@ -68,9 +68,9 @@ is
       end if;
 
       LI := Left.First;
-      RI := Left.First;
+      RI := Right.First;
       while LI /= 0 loop
-         if Left.Nodes (LI).Element /= Right.Nodes (LI).Element then
+         if Left.Nodes (LI).Element /= Right.Nodes (RI).Element then
             return False;
          end if;