Replace NULL macros with nullptr literals.

Change-Id: I918c40879aa547438f77e7d1a95fa2aa33bec398
diff --git a/cpp/ScriptC.cpp b/cpp/ScriptC.cpp
index 69d3bd5..d431355 100644
--- a/cpp/ScriptC.cpp
+++ b/cpp/ScriptC.cpp
@@ -23,7 +23,7 @@
                  const void *codeTxt, size_t codeLength,
                  const char *cachedName, size_t cachedNameLength,
                  const char *cacheDir, size_t cacheDirLength)
-: Script(NULL, rs) {
+: Script(nullptr, rs) {
     mID = RS::dispatch->ScriptCCreate(rs->getContext(), cachedName, cachedNameLength,
                                       rs->mCacheDir.c_str(), rs->mCacheDir.length(), (const char *)codeTxt, codeLength);
 }