patch 9.1.1173: filetype: ABNF files are not detected

Problem:  filetype: ABNF files are not detected
Solution: detect '.abnf' file as abnf filetype and
          include an abnf syntax plugin (A4-Tacks).

References:
- RFC5234
- RFC7405

closes: #16802

Signed-off-by: A4-Tacks <wdsjxhno1001@163.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

.github/MAINTAINERS

@@ -422,6 +422,7 @@ runtime/pack/dist/opt/nohlsearch/		@habamax
 runtime/plugin/manpager.vim		@Konfekt
 runtime/syntax/shared/hgcommitDiff.vim	@vegerot
 runtime/syntax/abaqus.vim		@costerwi
+runtime/syntax/abnf.vim		@A4-Tacks
 runtime/syntax/aidl.vim			@dpelle
 runtime/syntax/ant.vim			@dkearns
 runtime/syntax/antlr4.vim		@jiangyinzuo

runtime/filetype.vim

@@ -1,7 +1,7 @@
 " Vim support file to detect file types
 "
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2025 Feb 23
+" Last Change:	2025 Mar 05
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " Listen very carefully, I will say this only once
@@ -75,6 +75,9 @@ au BufNewFile,BufRead *.abc			setf abc
 " ABEL
 au BufNewFile,BufRead *.abl			setf abel
 
+" ABNF
+au BufNewFile,BufRead *.abnf			setf abnf
+
 " AceDB
 au BufNewFile,BufRead *.wrm			setf acedb
 

runtime/syntax/abnf.vim

@@ -0,0 +1,33 @@
+" Vim compiler file
+" Language:	abnf
+" Maintainer:	A4-Tacks <wdsjxhno1001@163.com>
+" Last Change:	2025 Mar 05
+" Upstream:	https://github.com/A4-Tacks/abnf.vim
+
+" Implementing RFC-5234, RFC-7405
+
+if exists('b:current_syntax')
+  finish
+endif
+
+syn case ignore
+
+syn match  abnfError	/[<>"]/
+syn match  abnfComment	/;.*/
+syn match  abnfOption	/[[/\]]/
+syn region abnfString	start=/\(%[si]\)\="/ end=/"/ oneline
+syn region abnfProse	start=/</ end=/>/ oneline
+syn match  abnfNumVal	/\v\%b[01]+%(%(\.[01]+)+|-[01]+)=>/
+syn match  abnfNumVal	/\v\%d\d+%(%(\.\d+)+|-\d+)=>/
+syn match  abnfNumVal	/\v\%x[0-9a-f]+%(%(\.[0-9a-f]+)+|-[0-9a-f]+)=>/
+syn match  abnfRepeat	/\v%(%(<\d+)=\*\d*|<\d+ =)\ze[^ \t\r\n0-9*/)\]]/
+
+hi def link abnfError		Error
+hi def link abnfComment		Comment
+hi def link abnfOption		PreProc
+hi def link abnfString		String
+hi def link abnfProse		String
+hi def link abnfNumVal		Number
+hi def link abnfRepeat		Repeat
+
+" vim:noet:ts=8:sts=8:nowrap

src/testdir/test_filetype.vim

@@ -87,6 +87,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     abap: ['file.abap'],
     abc: ['file.abc'],
     abel: ['file.abl'],
+    abnf: ['file.abnf'],
     acedb: ['file.wrm'],
     ada: ['file.adb', 'file.ads', 'file.ada', 'file.gpr'],
     ahdl: ['file.tdf'],

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1173,
 /**/
     1172,
 /**/