Replace NULL macros with nullptr literals.

Change-Id: I918c40879aa547438f77e7d1a95fa2aa33bec398
diff --git a/rsScriptIntrinsic.cpp b/rsScriptIntrinsic.cpp
index 7461d34..ee9d73c 100644
--- a/rsScriptIntrinsic.cpp
+++ b/rsScriptIntrinsic.cpp
@@ -64,7 +64,7 @@
                          size_t usrBytes,
                          const RsScriptCall* sc) {
 
-    if (rsc->mHal.funcs.script.invokeForEachMulti != NULL) {
+    if (rsc->mHal.funcs.script.invokeForEachMulti != nullptr) {
         rsc->mHal.funcs.script.invokeForEachMulti(rsc, this, slot, ains, inLen,
                                                   aout, usr, usrBytes, sc);
 
@@ -98,7 +98,7 @@
     ScriptIntrinsic *si = new ScriptIntrinsic(rsc);
     if (!si->init(rsc, (RsScriptIntrinsicID)id, (Element *)ve)) {
         delete si;
-        return NULL;
+        return nullptr;
     }
     si->incUserRef();
     return si;