Split RelativePatcher::ReserveSpace() into two.

Instead of passing nullptr and MethodReference(nullptr, 0u)
to ReserveSpace() at the end, call a newly created function
ReserveSpaceEnd().

Change-Id: I38815fe9464b4e1a919878b6e8577614f1058d00
diff --git a/compiler/linker/relative_patcher.h b/compiler/linker/relative_patcher.h
index 7a78254..8a9f3f8 100644
--- a/compiler/linker/relative_patcher.h
+++ b/compiler/linker/relative_patcher.h
@@ -82,11 +82,13 @@
     return size_misc_thunks_;
   }
 
-  // Reserve space for relative call thunks if needed, return adjusted offset. After all methods
-  // of a class have been processed it's called one last time with compiled_method == nullptr.
+  // Reserve space for thunks if needed before a method, return adjusted offset.
   virtual uint32_t ReserveSpace(uint32_t offset, const CompiledMethod* compiled_method,
                                 MethodReference method_ref) = 0;
 
+  // Reserve space for thunks if needed after the last method, return adjusted offset.
+  virtual uint32_t ReserveSpaceEnd(uint32_t offset) = 0;
+
   // Write relative call thunks if needed, return adjusted offset.
   virtual uint32_t WriteThunks(OutputStream* out, uint32_t offset) = 0;