Replace NULL with nullptr

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

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/runtime/utils.h b/runtime/utils.h
index 6708c67..853fa08 100644
--- a/runtime/utils.h
+++ b/runtime/utils.h
@@ -508,7 +508,7 @@
 
 // Find $ANDROID_DATA, /data, or abort.
 const char* GetAndroidData();
-// Find $ANDROID_DATA, /data, or return nullptr.
+// Find $ANDROID_DATA, /data, or return null.
 const char* GetAndroidDataSafe(std::string* error_msg);
 
 // Returns the dalvik-cache location, with subdir appended. Returns the empty string if the cache