Replace "iothread lock" with "BQL" in comments

The term "iothread lock" is obsolete. The APIs use Big QEMU Lock (BQL)
in their names. Update the code comments to use "BQL" instead of
"iothread lock".

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Message-id: 20240102153529.486531-5-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

ui/cocoa.m

@@ -113,7 +113,7 @@ static NSInteger cbchangecount = -1;
 static QemuClipboardInfo *cbinfo;
 static QemuEvent cbevent;
 
-// Utility functions to run specified code block with iothread lock held
+// Utility functions to run specified code block with the BQL held
 typedef void (^CodeBlock)(void);
 typedef bool (^BoolCodeBlock)(void);
 
@@ -548,7 +548,7 @@ static CGEventRef handleTapEvent(CGEventTapProxy proxy, CGEventType type, CGEven
 
 - (void) updateUIInfoLocked
 {
-    /* Must be called with the iothread lock, i.e. via updateUIInfo */
+    /* Must be called with the BQL, i.e. via updateUIInfo */
     NSSize frameSize;
     QemuUIInfo info;
 
@@ -2075,7 +2075,7 @@ static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
      * Create the menu entries which depend on QEMU state (for consoles
      * and removable devices). These make calls back into QEMU functions,
      * which is OK because at this point we know that the second thread
-     * holds the iothread lock and is synchronously waiting for us to
+     * holds the BQL and is synchronously waiting for us to
      * finish.
      */
     add_console_menu_entries();

ui/spice-core.c

@@ -217,7 +217,7 @@ static void channel_event(int event, SpiceChannelEventInfo *info)
      * not do that.  It isn't that easy to fix it in spice and even
      * when it is fixed we still should cover the already released
      * spice versions.  So detect that we've been called from another
-     * thread and grab the iothread lock if so before calling qemu
+     * thread and grab the BQL if so before calling qemu
      * functions.
      */
     bool need_lock = !qemu_thread_is_self(&me);