Switch to g_ for globals.

That's what the Google style guide recommends, and we're starting
to get a mix.

Change-Id: Ib0c53a890bb5deed5c679e887541a715faea91fc
diff --git a/libc/bionic/pthread_accessor.h b/libc/bionic/pthread_accessor.h
index ccb71bb..df4a5a2 100644
--- a/libc/bionic/pthread_accessor.h
+++ b/libc/bionic/pthread_accessor.h
@@ -26,7 +26,7 @@
  public:
   explicit pthread_accessor(pthread_t desired_thread) {
     Lock();
-    for (thread_ = gThreadList; thread_ != NULL; thread_ = thread_->next) {
+    for (thread_ = g_thread_list; thread_ != NULL; thread_ = thread_->next) {
       if (thread_ == reinterpret_cast<pthread_internal_t*>(desired_thread)) {
         break;
       }
@@ -41,7 +41,7 @@
     if (is_locked_) {
       is_locked_ = false;
       thread_ = NULL;
-      pthread_mutex_unlock(&gThreadListLock);
+      pthread_mutex_unlock(&g_thread_list_lock);
     }
   }
 
@@ -54,7 +54,7 @@
   bool is_locked_;
 
   void Lock() {
-    pthread_mutex_lock(&gThreadListLock);
+    pthread_mutex_lock(&g_thread_list_lock);
     is_locked_ = true;
   }