[Ada] Remove useless pragma Warnings Off from runtime units

[Pierre-Marie de Rodat via Gcc-patches]

GNAT does not issue a warning anymore on a postcondition of True (used
here to prevent inining inside GNATprove for proof).

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

gcc/ada/

        * libgnat/s-valuei.ads: Remove pragma Warnings Off.
        * libgnat/s-valueu.ads: Same.
        * libgnat/s-valuti.ads: Same.
diff --git a/gcc/ada/libgnat/s-valuei.ads b/gcc/ada/libgnat/s-valuei.ads
--- a/gcc/ada/libgnat/s-valuei.ads
+++ b/gcc/ada/libgnat/s-valuei.ads
@@ -37,8 +37,6 @@ pragma Assertion_Policy (Pre                => Ignore,
                          Contract_Cases     => Ignore,
                          Ghost              => Ignore,
                          Subprogram_Variant => Ignore);
-pragma Warnings (Off, "postcondition does not mention function result");
---  True postconditions are used to avoid inlining for GNATprove
 
 with System.Val_Util; use System.Val_Util;
 


diff --git a/gcc/ada/libgnat/s-valueu.ads b/gcc/ada/libgnat/s-valueu.ads
--- a/gcc/ada/libgnat/s-valueu.ads
+++ b/gcc/ada/libgnat/s-valueu.ads
@@ -43,8 +43,6 @@ pragma Assertion_Policy (Pre                => Ignore,
                          Contract_Cases     => Ignore,
                          Ghost              => Ignore,
                          Subprogram_Variant => Ignore);
-pragma Warnings (Off, "postcondition does not mention function result");
---  True postconditions are used to avoid inlining for GNATprove
 
 with System.Val_Util; use System.Val_Util;
 


diff --git a/gcc/ada/libgnat/s-valuti.ads b/gcc/ada/libgnat/s-valuti.ads
--- a/gcc/ada/libgnat/s-valuti.ads
+++ b/gcc/ada/libgnat/s-valuti.ads
@@ -41,8 +41,6 @@ pragma Assertion_Policy (Pre            => Ignore,
                          Post           => Ignore,
                          Contract_Cases => Ignore,
                          Ghost          => Ignore);
-pragma Warnings (Off, "postcondition does not mention function result");
---  True postconditions are used to avoid inlining for GNATprove
 
 with System.Case_Util;