Unify the invoke stubs and replace "oat" with "Art" in the API.

Change-Id: Ic1529d7568bd5297fdce4da69ede67c2f48487a4
diff --git a/src/compiler/Compiler.h b/src/compiler/Compiler.h
index a457fa6..9516f25 100644
--- a/src/compiler/Compiler.h
+++ b/src/compiler/Compiler.h
@@ -209,7 +209,7 @@
 
 }  // namespace art
 
-extern "C" art::CompiledMethod* oatCompileMethod(art::Compiler& compiler,
+extern "C" art::CompiledMethod* ArtCompileMethod(art::Compiler& compiler,
                                                  const art::DexFile::CodeItem* code_item,
                                                  uint32_t access_flags, uint32_t method_idx,
                                                  const art::ClassLoader* class_loader,