[Ada] Suppress warning in g-socthi__vxworks.adb

[Pierre-Marie de Rodat via Gcc-patches]

Follow-on to previous change, which missed the vxworks version of this
package.

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

gcc/ada/

        * libgnat/g-socthi__vxworks.adb (C_Connect): Suppress new warning.
diff --git a/gcc/ada/libgnat/g-socthi__vxworks.adb b/gcc/ada/libgnat/g-socthi__vxworks.adb
--- a/gcc/ada/libgnat/g-socthi__vxworks.adb
+++ b/gcc/ada/libgnat/g-socthi__vxworks.adb
@@ -190,7 +190,9 @@ package body GNAT.Sockets.Thin is
          return Res;
       end if;
 
-      declare
+      pragma Warnings (Off, "unreachable code");
+      declare -- unreachable if Thread_Blocking_IO is statically True
+         pragma Warnings (On, "unreachable code");
          WSet : aliased Fd_Set;
          Now  : aliased Timeval;
       begin