Replace NULL macros with nullptr literals.

Change-Id: I918c40879aa547438f77e7d1a95fa2aa33bec398
diff --git a/rsScriptC.h b/rsScriptC.h
index 5735bea..86de5b2 100644
--- a/rsScriptC.h
+++ b/rsScriptC.h
@@ -49,11 +49,11 @@
                             Allocation * aout,
                             const void * usr,
                             size_t usrBytes,
-                            const RsScriptCall *sc = NULL);
+                            const RsScriptCall *sc = nullptr);
 
     virtual void serialize(Context *rsc, OStream *stream) const {    }
     virtual RsA3DClassID getClassId() const { return RS_A3D_CLASS_ID_SCRIPT_C; }
-    static Type *createFromStream(Context *rsc, IStream *stream) { return NULL; }
+    static Type *createFromStream(Context *rsc, IStream *stream) { return nullptr; }
 
     bool runCompiler(Context *rsc, const char *resName, const char *cacheDir,
                      const uint8_t *bitcode, size_t bitcodeLen);