[CSRSS] Enable compilation of raise hard error function call code

With introduction of 74e527b, a330b56 and subsequently 2791ecd ReactOS can now properly set IOPL (I/O privilege level) for user mode trusted processes. With that said, enable the compilation of raise hard error function call code back.

subsystems/win32/csrss/csrss.c

@@ -10,6 +10,7 @@
 /* INCLUDES *******************************************************************/
 
 #define NTOS_MODE_USER
+#include <ndk/exfuncs.h>
 #include <ndk/psfuncs.h>
 #include <ndk/rtlfuncs.h>
 
@@ -42,7 +43,7 @@ _main(int argc,
 {
     KPRIORITY BasePriority = (8 + 1) + 4;
     NTSTATUS Status;
-    //ULONG Response; // see the #if 0
+    ULONG Response;
     UNREFERENCED_PARAMETER(envp);
     UNREFERENCED_PARAMETER(DebugFlag);
 
@@ -62,14 +63,12 @@ _main(int argc,
     {
         /* Raise a hard error */
         DPRINT1("CSRSS: Could not raise IOPL, Status: 0x%08lx\n", Status);
-#if 0
         Status = NtRaiseHardError(STATUS_IO_PRIVILEGE_FAILED,
                                   0,
                                   0,
                                   NULL,
                                   OptionOk,
                                   &Response);
-#endif
     }
 #endif