[x86] Avoid memory form of PUSH/CALL for ATOM.

src/base/cpu.h

Index: src/base/cpu.h
diff --git a/src/base/cpu.h b/src/base/cpu.h
index 38465f5b358f6654c8f4d28bdb5ce40954e41bbd..193ea5a921b0e7d78d9d71f29c97571bc6f8b35a 100644
--- a/src/base/cpu.h
+++ b/src/base/cpu.h
@@ -85,6 +85,7 @@ class CPU FINAL {
   bool has_sse42() const { return has_sse42_; }
   bool has_avx() const { return has_avx_; }
   bool has_fma3() const { return has_fma3_; }
+  bool is_atom() const { return is_atom_; }
 
   // arm features
   bool has_idiva() const { return has_idiva_; }
@@ -119,6 +120,7 @@ class CPU FINAL {
   bool has_ssse3_;
   bool has_sse41_;
   bool has_sse42_;
+  bool is_atom_;
   bool has_avx_;
   bool has_fma3_;
   bool has_idiva_;