Add a system() call to the d8 shell (Unix only).

samples/shell.cc

Index: samples/shell.cc
===================================================================
--- samples/shell.cc	(revision 1618)
+++ samples/shell.cc	(working copy)
@@ -1,4 +1,4 @@
-// Copyright 2008 the V8 project authors. All rights reserved.
+// Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -123,6 +123,7 @@
     printf("%s", cstr);
   }
   printf("\n");
+  fflush(stdout);
   return v8::Undefined();
 }