[llvm][NFC] Rework Timer.cpp globals to ensure valid lifetimes

Author: macurtis-amd

llvm/include/llvm/Support/Timer.h

@@ -12,13 +12,15 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Mutex.h"
 #include <cassert>
 #include <memory>
 #include <string>
 #include <vector>
 
 namespace llvm {
 
+class TimerGlobals;
 class TimerGroup;
 class raw_ostream;
 
@@ -196,6 +198,10 @@ class TimerGroup {
   TimerGroup(const TimerGroup &TG) = delete;
   void operator=(const TimerGroup &TG) = delete;
 
+  friend class TimerGlobals;
+  explicit TimerGroup(StringRef Name, StringRef Description,
+                      sys::SmartMutex<true> &lock);
+
 public:
   explicit TimerGroup(StringRef Name, StringRef Description);