patch 8.0.1445: cannot act on edits in the command line

Problem:    Cannot act on edits in the command line.
Solution:   Add the CmdlineChanged autocommand event. (xtal8, closes #2603,
            closes #2524)
diff --git a/src/fileio.c b/src/fileio.c
index ba9ec9e..fb5af64 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -7786,6 +7786,7 @@
     {"BufWritePost",	EVENT_BUFWRITEPOST},
     {"BufWritePre",	EVENT_BUFWRITEPRE},
     {"BufWriteCmd",	EVENT_BUFWRITECMD},
+    {"CmdlineChanged",	EVENT_CMDLINECHANGED},
     {"CmdlineEnter",	EVENT_CMDLINEENTER},
     {"CmdlineLeave",	EVENT_CMDLINELEAVE},
     {"CmdwinEnter",	EVENT_CMDWINENTER},