bug#55370: [PATCH] Add support for the Syloti Nagri script

[Eli Zaretskii <eliz@gnu.org>]

> From: समीर सिंह Sameer Singh <lumarzeli30@gmail.com>
> Date: Sun, 15 May 2022 20:11:28 +0530
> Cc: 55370@debbugs.gnu.org
> 
> They look alright to me.
> 1. ꠝꠥ (\xA81D\xA825) (buffer positions 2684 and 2685)
> C-u C-x = shows
> position: 2684 of 3952 (68%), column: 48
>             character: ꠝ (displayed as ꠝ) (codepoint 43037, #o124035, #xa81d)
>               charset: unicode (Unicode (ISO10646))
> code point in charset: 0xA81D
>                script: syloti-nagri
>                syntax: w which means: word
>              category: .:Base, L:Strong L2R
>              to input: type "C-x 8 RET a81d" or "C-x 8 RET SYLOTI NAGRI LETTER MO"
>           buffer code: #xEA #xA0 #x9D
>             file code: #xEA #xA0 #x9D (encoded by coding system utf-8-unix)
>               display: composed to form "ꠝꠥ" (see below)
> 
> Composed with the following character(s) "ꠥ" using this font:
>   ftcrhb:-GOOG-Noto Sans Syloti Nagri-regular-normal-normal-*-40-*-*-*-*-0-iso10646-1
> by these glyphs:
>   [0 1 43037 46 26 -1 27 28 1 nil]
>   [0 1 43045 54 0 -16 1 1 11 nil]
> with these character(s):
>   ꠥ (#xa825) SYLOTI NAGRI VOWEL SIGN U

It was because of the font I had installed, which I guess didn't
support some ligatures.

Thanks.