Fix x64 build after executable memory limit change.

src/spaces.h

Index: src/spaces.h
===================================================================
--- src/spaces.h	(revision 5799)
+++ src/spaces.h	(working copy)
@@ -492,7 +492,7 @@
  public:
   // Initializes its internal bookkeeping structures.
   // Max capacity of the total space and executable memory limit.
-  static bool Setup(int max_capacity, int capacity_executable);
+  static bool Setup(intptr_t max_capacity, intptr_t capacity_executable);
 
   // Deletes valid chunks.
   static void TearDown();