[Ada] Remove CodePeer annotations for pragma Loop_Variant

[Pierre-Marie de Rodat via Gcc-patches]

Pragma Loop_Variant is now expanded into a null statement in CodePeer
mode. Remove annotation related to false positives in runtime units.

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

gcc/ada/

        * libgnat/s-expmod.adb: Remove CodePeer annotation for pragma
        Loop_Variant.
diff --git a/gcc/ada/libgnat/s-expmod.adb b/gcc/ada/libgnat/s-expmod.adb
--- a/gcc/ada/libgnat/s-expmod.adb
+++ b/gcc/ada/libgnat/s-expmod.adb
@@ -251,9 +251,6 @@ is
             pragma Loop_Invariant (Equal_Modulo
               (Big (Result) * Big (Factor) ** Exp, Big (Left) ** Right));
             pragma Loop_Variant (Decreases => Exp);
-            pragma Annotate
-              (CodePeer, False_Positive,
-               "validity check", "confusion on generated code");
 
             if Exp rem 2 /= 0 then
                pragma Assert