[C++11] More 'nullptr' conversion. In some cases just using a boolean check instead of comparing to nullptr.

llvm-svn: 206252
diff --git a/llvm/lib/Support/Timer.cpp b/llvm/lib/Support/Timer.cpp
index ea75d45..eb3ffc4 100644
--- a/llvm/lib/Support/Timer.cpp
+++ b/llvm/lib/Support/Timer.cpp
@@ -100,7 +100,7 @@
 //===----------------------------------------------------------------------===//
 
 void Timer::init(StringRef N) {
-  assert(TG == 0 && "Timer already initialized");
+  assert(!TG && "Timer already initialized");
   Name.assign(N.begin(), N.end());
   Started = false;
   TG = getDefaultTimerGroup();
@@ -108,7 +108,7 @@
 }
 
 void Timer::init(StringRef N, TimerGroup &tg) {
-  assert(TG == 0 && "Timer already initialized");
+  assert(!TG && "Timer already initialized");
   Name.assign(N.begin(), N.end());
   Started = false;
   TG = &tg;