MC: Remove the copy of MCSchedModel in MCSubtargetInfo

`MCSchedModel` is large.  Make `MCSchedModel::GetDefaultSchedModel()`
return by-reference instead of by-value, so we can store a pointer in
`MCSubtargetInfo::CPUSchedModel` instead of a copy.

Note: since `MCSchedModel` is POD, this doesn't create a static
constructor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241947 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCSchedule.cpp

@@ -0,0 +1,33 @@
+//===- MCSchedule.cpp - Scheduling ------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the default scheduling model.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCSchedule.h"
+
+using namespace llvm;
+
+static_assert(std::is_pod<MCSchedModel>::value,
+              "We shouldn't have a static constructor here");
+const MCSchedModel MCSchedModel::Default = {DefaultIssueWidth,
+                                            DefaultMicroOpBufferSize,
+                                            DefaultLoopMicroOpBufferSize,
+                                            DefaultLoadLatency,
+                                            DefaultHighLatency,
+                                            DefaultMispredictPenalty,
+                                            false,
+                                            true,
+                                            0,
+                                            nullptr,
+                                            nullptr,
+                                            0,
+                                            0,
+                                            nullptr};