8341558: [AIX] build broken after 8341413

Reviewed-by: kbarrett

src/hotspot/os/aix/osThread_aix.cpp

@@ -40,7 +40,6 @@ OSThread::OSThread()
     _ucontext(nullptr),
     _expanding_stack(0),
     _alt_sig_stack(nullptr),
-    _last_cpu_times(),
     _startThread_lock(new Monitor(Mutex::event, "startThread_lock")) {
   sigemptyset(&_caller_sigmask);
 }

src/hotspot/os/aix/osThread_aix.hpp

@@ -131,13 +131,6 @@ class OSThread : public OSThreadBase {
     return _startThread_lock;
   }
 
-  // The last measured values of cpu timing to prevent the "stale
-  // value return" bug in thread_cpu_time.
-  volatile struct {
-    jlong sys;
-    jlong user;
-  } _last_cpu_times;
-
   // Printing
   uintx thread_id_for_printing() const override {
     return (uintx)_thread_id;