vim-patch:9.1.0306: filetype: x11vnc config file is not recognized

Problem:  filetype: x11vnc config file is not recognized
Solution: Detect '.x11vncrc' as conf filetype
          (Wu, Zhenyu)

See: https://linux.die.net/man/1/x11vnc

closes: vim/vim#14511

58ce78ad43

Co-authored-by: Wu, Zhenyu <wuzhenyu@ustc.edu>

runtime/lua/vim/filetype.lua

@@ -1302,6 +1302,7 @@ local filename = {
   ['csh.login'] = detect.csh,
   ['csh.logout'] = detect.csh,
   ['auto.master'] = 'conf',
+  ['.x11vncrc'] = 'conf',
   ['configure.in'] = 'config',
   ['configure.ac'] = 'config',
   crontab = 'crontab',