clang-tidy: Replace NULL with nullptr

Replaced all instances of NULL with nullptr to improve type safety
and clarity, as nullptr is the modern C++ standard for null pointers.

Tested: Build verified

Change-Id: Ib39f49b2a1239082eeac355234a65d7257031f10
Signed-off-by: Jayanth Othayoth <ojayanth@gmail.com>
diff --git a/utils.cpp b/utils.cpp
index 7744868..4e91a7d 100644
--- a/utils.cpp
+++ b/utils.cpp
@@ -43,7 +43,7 @@
                    const internal::DlSysInterface* sys)
 {
     std::unordered_set<HandlerFactory> seen;
-    void* libHandle = NULL;
+    void* libHandle = nullptr;
     HandlerFactory factory;
 
     std::vector<std::string> libs = getLibraryList(path, matchBlobHandler);