Add stack alignment check to ia32 and x64

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
===================================================================
--- src/x64/macro-assembler-x64.h	(revision 4427)
+++ src/x64/macro-assembler-x64.h	(working copy)
@@ -737,6 +737,9 @@
   // Print a message to stdout and abort execution.
   void Abort(const char* msg);
 
+  // Check that the stack is aligned.
+  void CheckStackAlignment();
+
   // Verify restrictions about code generated in stubs.
   void set_generating_stub(bool value) { generating_stub_ = value; }
   bool generating_stub() { return generating_stub_; }