Hello

  Emacs (emacs -Q with X11) segfaults in xfns.c (create_frame_xic), at 
its initialization, if XIM pointer is set, but not XIM_styles pointer.

  The patch extends the check on xim pointer to add the XIM_Styles 
pointer too.

  The code is at least several years old (git blame write "2014-03" in 
26.3 branch). The bug is present in master, 27.1-rc1 and 26.3 branch.

  The bug triggers today in my settings (emacs 26.3 from my debian/sid 
with gdm3 and windowmaker), but I do not know exactly why yet.

  Have a nice day
  Grégory Mounié