Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/compiler/elf_writer_test.cc b/compiler/elf_writer_test.cc
index 3e5ad7b..08523d8 100644
--- a/compiler/elf_writer_test.cc
+++ b/compiler/elf_writer_test.cc
@@ -55,12 +55,12 @@
   LOG(INFO) << "elf_filename=" << elf_filename;
 
   UnreserveImageSpace();
-  void* dl_oatdata = NULL;
-  void* dl_oatexec = NULL;
-  void* dl_oatlastword = NULL;
+  void* dl_oatdata = nullptr;
+  void* dl_oatexec = nullptr;
+  void* dl_oatlastword = nullptr;
 
   std::unique_ptr<File> file(OS::OpenFileForReading(elf_filename.c_str()));
-  ASSERT_TRUE(file.get() != NULL);
+  ASSERT_TRUE(file.get() != nullptr);
   {
     std::string error_msg;
     std::unique_ptr<ElfFile> ef(ElfFile::Open(file.get(), false, false, &error_msg));