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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206252 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/ManagedStatic.cpp

@@ -45,7 +45,7 @@ void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
 
     llvm_release_global_lock();
   } else {
-    assert(Ptr == 0 && DeleterFn == 0 && Next == 0 &&
+    assert(!Ptr && !DeleterFn && !Next &&
            "Partially initialized ManagedStatic!?");
     Ptr = Creator ? Creator() : nullptr;
     DeleterFn = Deleter;