Refactor: Simplify boolean expressions in libclang

Simplify boolean expresions using true and false with clang-tidy.

Patch by Richard.

llvm-svn: 232996

clang/tools/libclang/CIndex.cpp

@@ -1718,7 +1718,7 @@ public:
     return VJ->getKind() == DeclVisitKind;
   }
   const Decl *get() const { return static_cast<const Decl *>(data[0]); }
-  bool isFirst() const { return data[1] ? true : false; }
+  bool isFirst() const { return data[1] != nullptr; }
 };
 class TypeLocVisit : public VisitorJob {
 public: