Method prologue and epilogues, add missing x86 functionality.

Enables compiling and running a number of JNI internal managed code
methods on the host.

Change-Id: I56fceb813d0cb24637bc784ba57f2d1d16911d48
diff --git a/src/calling_convention_x86.h b/src/calling_convention_x86.h
index cb2b89a..4bca318 100644
--- a/src/calling_convention_x86.h
+++ b/src/calling_convention_x86.h
@@ -37,8 +37,9 @@
   virtual bool IsCurrentParamOnStack();
   virtual ManagedRegister CurrentParamRegister();
   virtual FrameOffset CurrentParamStackOffset();
-
+  virtual const std::vector<ManagedRegister>& EntrySpills();
  private:
+  std::vector<ManagedRegister> entry_spills_;
   DISALLOW_COPY_AND_ASSIGN(X86ManagedRuntimeCallingConvention);
 };