patch 9.1.1909: filetype: .mom files recognized as nroff files

Problem:  filetype: .mom files recognized as nroff files
Solution: Detect *.mom files as groff filetype instead
          (Callum Andrew)

Reference:
- mom macros are written specifically for groff:
  https://www.schaffter.ca/mom/

closes: #18718

Signed-off-by: Callum Andrew <dev@candrew.net>
Signed-off-by: Christian Brabandt <cb@256bit.org>

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 Oct 09
+" Last Change:		2025 Nov 11
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " If the filetype can be detected from extension or file name(the final path component),
@@ -774,12 +774,13 @@ au BufNewFile,BufRead */neofetch/config.conf	setf sh
 " Nginx
 au BufNewFile,BufRead *.nginx,nginx*.conf,*nginx.conf,*/nginx/*.conf	setf nginx
 
-" Nroff/Troff (*.ms and *.t are checked below)
+" Nroff/Groff/Troff (*.ms and *.t are checked below)
 au BufNewFile,BufRead *.me
 	\ if expand("<afile>") != "read.me" && expand("<afile>") != "click.me" |
 	\   setf nroff |
 	\ endif
-au BufNewFile,BufRead *.tr,*.nr,*.roff,*.tmac,*.mom	setf nroff
+au BufNewFile,BufRead *.tr,*.nr,*.roff,*.tmac setf nroff
+au BufNewFile,BufRead *.groff,*.mom setf groff
 au BufNewFile,BufRead *.[0-9],*.[013]p,*.[1-8]x,*.3{am,perl,pm,posix,type},*.n	call dist#ft#FTnroff()
 
 " Nroff or Objective C++

src/testdir/test_filetype.vim

@@ -343,6 +343,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     grads: ['file.gs'],
     graphql: ['file.graphql', 'file.graphqls', 'file.gql'],
     gretl: ['file.gretl'],
+    groff: ['file.groff', 'file.mom'],
     groovy: ['file.gradle', 'file.groovy', 'Jenkinsfile'],
     group: ['any/etc/group', 'any/etc/group-', 'any/etc/group.edit', 'any/etc/gshadow', 'any/etc/gshadow-', 'any/etc/gshadow.edit', 'any/var/backups/group.bak', 'any/var/backups/gshadow.bak', '/etc/group', '/etc/group-', '/etc/group.edit', '/etc/gshadow', '/etc/gshadow-', '/etc/gshadow.edit', '/var/backups/group.bak', '/var/backups/gshadow.bak'],
     grub: ['/boot/grub/menu.lst', '/boot/grub/grub.conf', '/etc/grub.conf', 'any/boot/grub/grub.conf', 'any/boot/grub/menu.lst', 'any/etc/grub.conf'],
@@ -576,7 +577,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     nix: ['file.nix'],
     norg: ['file.norg'],
     nqc: ['file.nqc'],
-    nroff: ['file.tr', 'file.nr', 'file.roff', 'file.tmac', 'file.mom', 'tmac.file'],
+    nroff: ['file.tr', 'file.nr', 'file.roff', 'file.tmac', 'tmac.file'],
     nsis: ['file.nsi', 'file.nsh'],
     ntriples: ['file.nt'],
     nu: ['file.nu'],

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1909,
 /**/
     1908,
 /**/