Remove some non-const references in utils

Change-Id: Ib2d3c39fadb6a750c68c37b0aa53daab155a65a3
diff --git a/runtime/utils.h b/runtime/utils.h
index c506fba..34e9459 100644
--- a/runtime/utils.h
+++ b/runtime/utils.h
@@ -323,10 +323,10 @@
 std::string GetThreadName(pid_t tid);
 
 // Returns details of the given thread's stack.
-void GetThreadStack(pthread_t thread, void*& stack_base, size_t& stack_size);
+void GetThreadStack(pthread_t thread, void** stack_base, size_t* stack_size);
 
 // Reads data from "/proc/self/task/${tid}/stat".
-void GetTaskStats(pid_t tid, char& state, int& utime, int& stime, int& task_cpu);
+void GetTaskStats(pid_t tid, char* state, int* utime, int* stime, int* task_cpu);
 
 // Returns the name of the scheduler group for the given thread the current process, or the empty string.
 std::string GetSchedulerGroupName(pid_t tid);