[C++11] Replace some comparisons with 'nullptr' with simple boolean checks to reduce verbosity.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205829 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/ManagedStatic.cpp

@@ -24,7 +24,7 @@ void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
   if (llvm_is_multithreaded()) {
     llvm_acquire_global_lock();
 
-    if (Ptr == nullptr) {
+    if (!Ptr) {
       void* tmp = Creator ? Creator() : nullptr;
 
       TsanHappensBefore(this);