6679708: No_Safepoint_Verifier and BacktraceBuilder have uninitialized fields

Summary: fix or remove uninitialized fields
Reviewed-by: kvn, rasbold

src/share/vm/classfile/javaClasses.cpp

@@ -1015,7 +1015,6 @@ class BacktraceBuilder: public StackObj {
   typeArrayOop    _bcis;
   int             _index;
   bool            _dirty;
-  bool            _done;
   No_Safepoint_Verifier _nsv;
 
  public:
@@ -1029,12 +1028,10 @@ class BacktraceBuilder: public StackObj {
   };
 
   // constructor for new backtrace
-  BacktraceBuilder(TRAPS): _methods(NULL), _bcis(NULL), _head(NULL) {
+  BacktraceBuilder(TRAPS): _methods(NULL), _bcis(NULL), _head(NULL), _dirty(false) {
     expand(CHECK);
     _backtrace = _head;
     _index = 0;
-    _dirty = false;
-    _done = false;
   }
 
   void flush() {

src/share/vm/memory/gcLocker.hpp

@@ -184,7 +184,9 @@ class No_Safepoint_Verifier : public No_GC_Verifier {
   Thread *_thread;
  public:
 #ifdef ASSERT
-  No_Safepoint_Verifier(bool activated = true, bool verifygc = true ) : No_GC_Verifier(verifygc) {
+  No_Safepoint_Verifier(bool activated = true, bool verifygc = true ) :
+    No_GC_Verifier(verifygc),
+    _activated(activated) {
     _thread = Thread::current();
     if (_activated) {
       _thread->_allow_allocation_count++;