patch 9.0.1039: using a <Cmd> mapping CmdlineChanged may be triggered twice

Problem:    Using a <Cmd> mapping CmdlineChanged may be triggered twice.
Solution:   Count the number of times CmdlineChanged is triggered and avoid
            doing it twice. (closes #116820
diff --git a/src/autocmd.c b/src/autocmd.c
index aca990c..20c5afa 100644
--- a/src/autocmd.c
+++ b/src/autocmd.c
@@ -2068,6 +2068,9 @@
 		&& (event == EVENT_WINLEAVE || event == EVENT_BUFLEAVE)))
 	goto BYPASS_AU;
 
+    if (event == EVENT_CMDLINECHANGED)
+	++aucmd_cmdline_changed_count;
+
     /*
      * Save the autocmd_* variables and info about the current buffer.
      */
@@ -2088,8 +2091,8 @@
     if (fname_io == NULL)
     {
 	if (event == EVENT_COLORSCHEME || event == EVENT_COLORSCHEMEPRE
-						   || event == EVENT_OPTIONSET
-						   || event == EVENT_MODECHANGED)
+						 || event == EVENT_OPTIONSET
+						 || event == EVENT_MODECHANGED)
 	    autocmd_fname = NULL;
 	else if (fname != NULL && !ends_excmd(*fname))
 	    autocmd_fname = fname;