qemu-thread: introduce QemuRecMutex

GRecMutex is new in glib 2.32, so we cannot use it.  Introduce
a recursive mutex in qemu-thread instead, which will be used
instead of RFifoLock.

Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-20-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>

util/qemu-thread-win32.c

@@ -79,6 +79,31 @@ void qemu_mutex_unlock(QemuMutex *mutex)
     LeaveCriticalSection(&mutex->lock);
 }
 
+void qemu_rec_mutex_init(QemuRecMutex *mutex)
+{
+    InitializeCriticalSection(&mutex->lock);
+}
+
+void qemu_rec_mutex_destroy(QemuRecMutex *mutex)
+{
+    DeleteCriticalSection(&mutex->lock);
+}
+
+void qemu_rec_mutex_lock(QemuRecMutex *mutex)
+{
+    EnterCriticalSection(&mutex->lock);
+}
+
+int qemu_rec_mutex_trylock(QemuRecMutex *mutex)
+{
+    return !TryEnterCriticalSection(&mutex->lock);
+}
+
+void qemu_rec_mutex_unlock(QemuRecMutex *mutex)
+{
+    LeaveCriticalSection(&mutex->lock);
+}
+
 void qemu_cond_init(QemuCond *cond)
 {
     memset(cond, 0, sizeof(*cond));