patch 9.1.1935: filetype: not all Erlang files are recognized

Problem:  filetype: not all Erlang files are recognized
Solution: Detect *.app.src and rebar.config files as erlang filetype
          (John Parise).

*.app.src files contain Erlang application definitions. (There are also
*.app files, which are similar but more often build artifacts, and that
file extension is too ambiguous to be recognized by default.)

Reference:
- https://www.erlang.org/doc/system/applications.html

Rebar is the Erlang build tool. rebar.config uses Erlang syntax.

Reference:
- https://rebar3.org/docs/configuration/configuration/

closes: #18835

Signed-off-by: Jon Parise <jon@indelible.org>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/autoload/dist/ft.vim

@@ -3,7 +3,7 @@ vim9script
 # Vim functions for file type detection
 #
 # Maintainer:		The Vim Project <https://github.com/vim/vim>
-# Last Change:		2025 Nov 28
+# Last Change:		2025 Nov 30
 # Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 # These functions are moved here from runtime/filetype.vim to make startup
@@ -3072,6 +3072,8 @@ const ft_from_name = {
   ".editorconfig": "editorconfig",
   # Elinks configuration
   "elinks.conf": "elinks",
+  # Erlang
+  "rebar.config": "erlang",
   # Exim
   "exim.conf": "exim",
   # Exports

runtime/filetype.vim

@@ -427,6 +427,9 @@ au BufNewFile,BufRead *.e,*.E			call dist#ft#FTe()
 " Elm Filter Rules file
 au BufNewFile,BufRead filter-rules		setf elmfilt
 
+" Erlang
+au BufNewFile,BufRead *.app.src			setf erlang
+
 " ESMTP rc file
 au BufNewFile,BufRead *esmtprc			setf esmtprc
 

src/testdir/test_filetype.vim

@@ -275,7 +275,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     elsa: ['file.lc'],
     elvish: ['file.elv'],
     epuppet: ['file.epp'],
-    erlang: ['file.erl', 'file.hrl', 'file.yaws'],
+    erlang: ['file.erl', 'file.hrl', 'file.yaws', 'file.app.src', 'rebar.config'],
     eruby: ['file.erb', 'file.rhtml'],
     esdl: ['file.esdl'],
     esmtprc: ['anyesmtprc', 'esmtprc', 'some-esmtprc'],

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1935,
 /**/
     1934,
 /**/