qemu-char: initialize chr_write_lock

Otherwise, Windows fails with a deadlock.
Reported-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1403679897-11480-1-git-send-email-pbonzini@redhat.com
Tested-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

qemu-char.c

@@ -94,6 +94,7 @@ static QTAILQ_HEAD(CharDriverStateHead, CharDriverState) chardevs =
 CharDriverState *qemu_chr_alloc(void)
 {
     CharDriverState *chr = g_malloc0(sizeof(CharDriverState));
+    qemu_mutex_init(&chr->chr_write_lock);
     return chr;
 }