imstb_truetype: Add missing `return` keyword in error case of `stbtt__cid_get_glyph_subrs` (#6007)

Submitted as PR: https://github.com/nothings/stb/pull/1422
Signed-off-by: Neil Bickford <nbickford@nvidia.com>

imstb_truetype.h

@@ -2008,7 +2008,7 @@ static stbtt__buf stbtt__cid_get_glyph_subrs(const stbtt_fontinfo *info, int gly
          start = end;
       }
    }
-   if (fdselector == -1) stbtt__new_buf(NULL, 0);
+   if (fdselector == -1) return stbtt__new_buf(NULL, 0); // [DEAR IMGUI] fixed, see #6007 and nothings/stb#1422
    return stbtt__get_subrs(info->cff, stbtt__cff_index_get(info->fontdicts, fdselector));
 }