minor struct optimization per feedback

from jsquyres

Signed-off-by: Howard Pritchard <hppritcha@gmail.com>

Author: hppritcha

opal/mca/threads/pthreads/threads_pthreads_mutex.c

@@ -40,15 +40,15 @@ struct opal_pthread_mutex_t {
     opal_object_t super;
 
     pthread_mutex_t m_lock_pthread;
+    opal_atomic_lock_t m_lock_atomic;
 
 #if OPAL_ENABLE_DEBUG
     int m_lock_debug;
     const char *m_lock_file;
     int m_lock_line;
 #endif
-
-    opal_atomic_lock_t m_lock_atomic;
 };
+
 typedef struct opal_pthread_mutex_t opal_pthread_mutex_t;
 typedef struct opal_pthread_mutex_t opal_pthread_recursive_mutex_t;