patch 8.0.1206: no autocmd for entering or leaving the command line

Problem:    No autocmd for entering or leaving the command line.
Solution:   Add CmdlineEnter and CmdlineLeave.
diff --git a/src/fileio.c b/src/fileio.c
index 0d1ac2d..5755156 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -7731,6 +7731,8 @@
     {"BufWritePost",	EVENT_BUFWRITEPOST},
     {"BufWritePre",	EVENT_BUFWRITEPRE},
     {"BufWriteCmd",	EVENT_BUFWRITECMD},
+    {"CmdlineEnter",	EVENT_CMDLINEENTER},
+    {"CmdlineLeave",	EVENT_CMDLINELEAVE},
     {"CmdwinEnter",	EVENT_CMDWINENTER},
     {"CmdwinLeave",	EVENT_CMDWINLEAVE},
     {"CmdUndefined",	EVENT_CMDUNDEFINED},