Fix Clang-tidy modernize-use-nullptr warnings in examples and include directories; other minor cleanups.

Patch by Eugene Zelenko!

Differential Revision: http://reviews.llvm.org/D13172

llvm-svn: 248811
diff --git a/llvm/examples/Fibonacci/fibonacci.cpp b/llvm/examples/Fibonacci/fibonacci.cpp
index 8092e19..a628cee 100644
--- a/llvm/examples/Fibonacci/fibonacci.cpp
+++ b/llvm/examples/Fibonacci/fibonacci.cpp
@@ -33,6 +33,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/raw_ostream.h"
+
 using namespace llvm;
 
 static Function *CreateFibFunction(Module *M, LLVMContext &Context) {
@@ -41,7 +42,7 @@
   Function *FibF =
     cast<Function>(M->getOrInsertFunction("fib", Type::getInt32Ty(Context),
                                           Type::getInt32Ty(Context),
-                                          (Type *)0));
+                                          nullptr));
 
   // Add a basic block to the function.
   BasicBlock *BB = BasicBlock::Create(Context, "EntryBlock", FibF);
@@ -87,7 +88,6 @@
   return FibF;
 }
 
-
 int main(int argc, char **argv) {
   int n = argc > 1 ? atol(argv[1]) : 24;