[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/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
index 999bf28..d53704f 100644
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -111,7 +111,7 @@
 
   // Check to see if this is past the end of the archive.
   if (NextLoc >= Parent->Data->getBufferEnd())
-    return Child(Parent, NULL);
+    return Child(Parent, nullptr);
 
   return Child(Parent, NextLoc);
 }
@@ -349,7 +349,7 @@
 }
 
 Archive::child_iterator Archive::child_end() const {
-  return Child(this, NULL);
+  return Child(this, nullptr);
 }
 
 error_code Archive::Symbol::getName(StringRef &Result) const {