bug#10867: 26.3; XIM preedit/status font handling

[Yichao Yu <yyc1992@gmail.com>]

> ## What other programs do
> * xterm seems to use "fixed" to lookup font
> * qt4 https://dreamswork.github.io/qt4/qximinputcontext__x11_8cpp_source.html
> AFAICT uses different fonts?
> * gtk I don't actually see where it set fonts...
> @Xuetian Weng dug deeper into this
>
> ## Fix
> I'm not sure what's the correct one. It seems that setting the fontSet
> is necessary although I'm not sure how/if gtk get away with it.
> According to @Xuetian Weng virtually no one use this setting anymore
> so setting a dummy value to comfort xlib might be good enough? It
> would avoid both issues at the same time.

And since it's basically a useless setting at this point, this fix seems to work

diff --git a/src/xfns.c b/src/xfns.c
index 2ab5080d97..fbbc429fe1 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -2511,72 +2511,19 @@ xic_create_xfontset (struct frame *f)

   if (! xfs)
     {
-      char buf[256];
       char **missing_list;
       int missing_count;
       char *def_string;
-      const char *xlfd_format = "-*-*-medium-r-normal--%d-*-*-*-*-*";
+      const char *last_resort = "fixed";

-      sprintf (buf, xlfd_format, pixel_size);
       missing_list = NULL;
-      xfs = XCreateFontSet (FRAME_X_DISPLAY (f), buf,
+      xfs = XCreateFontSet (FRAME_X_DISPLAY (f), last_resort,
      &missing_list, &missing_count, &def_string);
 #ifdef DEBUG_XIC_FONTSET
-      print_fontset_result (xfs, buf, missing_list, missing_count);
+      print_fontset_result (xfs, last_resort, missing_list, missing_count);
 #endif
       if (missing_list)
- XFreeStringList (missing_list);
-      if (! xfs)
- {
-   /* List of pixel sizes most likely available.  Find one that
-      is closest to pixel_size.  */
-   int sizes[] = {0, 8, 10, 11, 12, 14, 17, 18, 20, 24, 26, 34, 0};
-   int *smaller, *larger;
-
-   for (smaller = sizes; smaller[1]; smaller++)
-     if (smaller[1] >= pixel_size)
-       break;
-   larger = smaller + 1;
-   if (*larger == pixel_size)
-     larger++;
-   while (*smaller || *larger)
-     {
-       int this_size;
-
-       if (! *larger)
- this_size = *smaller--;
-       else if (! *smaller)
- this_size = *larger++;
-       else if (pixel_size - *smaller < *larger - pixel_size)
- this_size = *smaller--;
-       else
- this_size = *larger++;
-       sprintf (buf, xlfd_format, this_size);
-       missing_list = NULL;
-       xfs = XCreateFontSet (FRAME_X_DISPLAY (f), buf,
-     &missing_list, &missing_count, &def_string);
-#ifdef DEBUG_XIC_FONTSET
-       print_fontset_result (xfs, buf, missing_list, missing_count);
-#endif
-       if (missing_list)
- XFreeStringList (missing_list);
-       if (xfs)
- break;
-     }
- }
-      if (! xfs)
- {
-   const char *last_resort = "-*-*-*-r-normal--*-*-*-*-*-*";
-
-   missing_list = NULL;
-   xfs = XCreateFontSet (FRAME_X_DISPLAY (f), last_resort,
- &missing_list, &missing_count, &def_string);
-#ifdef DEBUG_XIC_FONTSET
-   print_fontset_result (xfs, last_resort, missing_list, missing_count);
-#endif
-   if (missing_list)
-     XFreeStringList (missing_list);
- }
+   XFreeStringList (missing_list);

     }