Fix MThreads startup by making the thread list dynamically init

It seems that a static thread definition (such as logThread in logging.cpp
amongst others) can end up using the MThread ctor before the statics for
the s_all_threads_lock and s_all_threads are initialized, causing a crash on
startup in some situations.

To get around this, I've changed them to be null initialized pointers (so they
are initialized statically and earlier), and initialize them on first MThread
ctor call as necessary.  There may be a more graceful fix, but this works.

In MThread::Cleanup(), a small restructure was needed such that the lock on
s_all_threads_lock can be unlocked before we delete it.

mythtv/libs/libmythbase/mthread.cpp

@@ -93,25 +93,37 @@ class MThreadInternal : public QThread
     MThread &m_parent;
 };
 
-static QMutex s_all_threads_lock;
-static QSet<MThread*> s_all_threads;
+static QMutex *s_all_threads_lock = NULL;
+static QSet<MThread*> *s_all_threads = NULL;
 
 MThread::MThread(const QString &objectName) :
     m_thread(new MThreadInternal(*this)), m_runnable(NULL),
     m_prolog_executed(true), m_epilog_executed(true)
 {
     m_thread->setObjectName(objectName);
-    QMutexLocker locker(&s_all_threads_lock);
-    s_all_threads.insert(this);
+    if (!s_all_threads_lock)
+        s_all_threads_lock = new QMutex;
+
+    QMutexLocker locker(s_all_threads_lock);
+    if (!s_all_threads)
+        s_all_threads = new QSet<MThread*>;
+
+    s_all_threads->insert(this);
 }
 
 MThread::MThread(const QString &objectName, QRunnable *runnable) :
     m_thread(new MThreadInternal(*this)), m_runnable(runnable),
     m_prolog_executed(false), m_epilog_executed(false)
 {
     m_thread->setObjectName(objectName);
-    QMutexLocker locker(&s_all_threads_lock);
-    s_all_threads.insert(this);
+    if (!s_all_threads_lock)
+        s_all_threads_lock = new QMutex;
+
+    QMutexLocker locker(s_all_threads_lock);
+    if (!s_all_threads)
+        s_all_threads = new QSet<MThread*>;
+
+    s_all_threads->insert(this);
 }
 
 MThread::~MThread()
@@ -132,8 +144,8 @@ MThread::~MThread()
     }
 
     {
-        QMutexLocker locker(&s_all_threads_lock);
-        s_all_threads.remove(this);
+        QMutexLocker locker(s_all_threads_lock);
+        s_all_threads->remove(this);
     }
 
     delete m_thread;
@@ -142,55 +154,63 @@ MThread::~MThread()
 
 void MThread::Cleanup(void)
 {
-    QMutexLocker locker(&s_all_threads_lock);
-    QSet<MThread*> badGuys;
-    QSet<MThread*>::const_iterator it;
-    for (it = s_all_threads.begin(); it != s_all_threads.end(); ++it)
     {
-        if ((*it)->isRunning())
+        QMutexLocker locker(s_all_threads_lock);
+        QSet<MThread*> badGuys;
+        QSet<MThread*>::const_iterator it;
+        for (it = s_all_threads->begin(); it != s_all_threads->end(); ++it)
         {
-            badGuys.insert(*it);
-            (*it)->exit(1);
+            if ((*it)->isRunning())
+            {
+                badGuys.insert(*it);
+                (*it)->exit(1);
+            }
         }
-    }
 
-    if (badGuys.empty())
-        return;
-
-    // logging has been stopped so we need to use iostream...
-    cerr<<"Error: Not all threads were shut down properly: "<<endl;
-    for (it = badGuys.begin(); it != badGuys.end(); ++it)
-    {
-        cerr<<"Thread "<<qPrintable((*it)->objectName())
-            <<" is still running"<<endl;
+        if (!badGuys.empty())
+        {
+            // logging has been stopped so we need to use iostream...
+            cerr<<"Error: Not all threads were shut down properly: "<<endl;
+            for (it = badGuys.begin(); it != badGuys.end(); ++it)
+            {
+                cerr<<"Thread "<<qPrintable((*it)->objectName())
+                    <<" is still running"<<endl;
+            }
+            cerr<<endl;
+
+            static const int kTimeout = 5000;
+            MythTimer t;
+            t.start();
+            for (it = badGuys.begin();
+                 it != badGuys.end() && t.elapsed() < kTimeout; ++it)
+            {
+                int left = kTimeout - t.elapsed();
+                if (left > 0)
+                    (*it)->wait(left);
+            }
+        }
     }
-    cerr<<endl;
 
-    static const int kTimeout = 5000;
-    MythTimer t;
-    t.start();
-    for (it = badGuys.begin();
-         it != badGuys.end() && t.elapsed() < kTimeout; ++it)
-    {
-        int left = kTimeout - t.elapsed();
-        if (left > 0)
-            (*it)->wait(left);
-    }
+    delete s_all_threads;
+    s_all_threads = NULL;
+
+    delete s_all_threads_lock;
+    s_all_threads_lock = NULL;
 }
 
 void MThread::GetAllThreadNames(QStringList &list)
 {
-    QMutexLocker locker(&s_all_threads_lock);
+    QMutexLocker locker(s_all_threads_lock);
     QSet<MThread*>::const_iterator it;
-    for (it = s_all_threads.begin(); it != s_all_threads.end(); ++it)
+    for (it = s_all_threads->begin(); it != s_all_threads->end(); ++it)
         list.push_back((*it)->objectName());
 }
 
 void MThread::GetAllRunningThreadNames(QStringList &list)
 {
-    QMutexLocker locker(&s_all_threads_lock);
+    QMutexLocker locker(s_all_threads_lock);
     QSet<MThread*>::const_iterator it;
-    for (it = s_all_threads.begin(); it != s_all_threads.end(); ++it)
+    for (it = s_all_threads->begin(); it != s_all_threads->end(); ++it)
     {
         if ((*it)->isRunning())
             list.push_back((*it)->objectName());