bug#58098: Improve composition rules for Gumrukhi

[Eli Zaretskii <eliz@gnu.org>]

> From: समीर सिंह Sameer Singh <lumarzeli30@gmail.com>
> Date: Tue, 27 Sep 2022 20:54:22 +0530
> Cc: 58098@debbugs.gnu.org
> 
>  The form
> 
>         (chess-symbol #x1FA00 #x1FA67)
> 
>  requires that _both_ #x1FA00 and #x1FA67 be supported by a font, for
>  it to be eligible to display chess-symbols.  By contrast, the form
> 
>         (chess-symbol . [#x1FA00 #x1FA67])
> 
>  requires that _either_ of the two characters is supported.  So my
>  question is: do we really want _both_ of the characters supported by a
>  font, and if not, do we really want Emacs to reject such a font?
> 
>  I have updated the patch accordingly and replaced (chess-symbol #x1FA00 #x1FA67) with 
>  (chess-symbol . [#x1FA00 #x1FA67])
> 
>  > You don't have Symbola installed?
> 
>  I have the Symbola font installed via the gdouros-symbola-fonts package on my Fedora37 system, but
>  it does not seem to support
>  the chess-symbols block as verified by hb-view.
>  Its description in the fedora wiki also does not mention the chess-symbols block:
> 
>  Symbola covers the following scripts and symbols supported by The Unicode Standard 5.2:
>  Basic Latin, Latin-1 Supplement, Latin Extended-A, IPA Extensions, Spacing Modifier Letters,
>  Greek and Coptic, Cyrillic, Cyrillic Supplementary, General Punctuation, Superscripts and
>  Subscripts, Combining Diacritical Marks for Symbols, Letterlike Symbols, Number Forms,
>  Arrows, Mathematical Operators, Miscellaneous Technical, Control Pictures, Optical Character
>  Recognition, Box Drawing, Block Elements, Geometric Shapes, Miscellaneous Symbols,
>  Dingbats, Miscellaneous Mathematical Symbols-A, Supplemental Arrows-A, Supplemental
>  Arrows-B, Miscellaneous Mathematical Symbols-B, Supplemental Mathematical Operators,
>  Miscellaneous Symbols and Arrows, Supplemental Punctuation, CJK Symbols and Punctuation,
>  Yijing Hexagram Symbols, Vertical Forms, Combining Half Marks, CJK Compatibility Forms,
>  Specials, Tai Xuan Jing Symbols, Counting Rod Numerals, Mathematical Alphanumeric
>  Symbols, Mahjong Tile Symbols, Domino Tile Symbols. 

OK, I installed this on master.