Allow platforms (linux and win32) to not force 16-byte alignment...

src/platform-linux.cc

Index: src/platform-linux.cc
===================================================================
--- src/platform-linux.cc	(revision 358)
+++ src/platform-linux.cc	(working copy)
@@ -194,8 +194,17 @@
 }
 
 
-double OS::nan_value() { return NAN; }
+double OS::nan_value() {
+  return NAN;
+}
 
+
+int OS::ActivationFrameAlignment() {
+  // No constraint on Linux.
+  return 0;
+}
+
+
 // We keep the lowest and highest addresses mapped as a quick way of
 // determining that pointers are outside the heap (used mostly in assertions
 // and verification).  The estimate is conservative, ie, not all addresses in