patch 8.1.0498: /etc/gitconfig not recognized at a gitconfig file

Problem:    /etc/gitconfig not recognized at a gitconfig file.
Solution:   Add pattern to filetype detection. (closes #3568)

Author: brammool

runtime/filetype.vim

@@ -613,12 +613,12 @@ au BufNewFile,BufRead *.mo,*.gdmo		setf gdmo
 au BufNewFile,BufRead *.ged,lltxxxxx.txt	setf gedcom
 
 " Git
-au BufNewFile,BufRead COMMIT_EDITMSG,MERGE_MSG,TAG_EDITMSG setf gitcommit
-au BufNewFile,BufRead *.git/config,.gitconfig,.gitmodules setf gitconfig
-au BufNewFile,BufRead *.git/modules/*/config	setf gitconfig
-au BufNewFile,BufRead */.config/git/config	setf gitconfig
+au BufNewFile,BufRead COMMIT_EDITMSG,MERGE_MSG,TAG_EDITMSG 	setf gitcommit
+au BufNewFile,BufRead *.git/config,.gitconfig,/etc/gitconfig 	setf gitconfig
+au BufNewFile,BufRead */.config/git/config			setf gitconfig
+au BufNewFile,BufRead .gitmodules,*.git/modules/*/config	setf gitconfig
 if !empty($XDG_CONFIG_HOME)
-  au BufNewFile,BufRead $XDG_CONFIG_HOME/git/config	setf gitconfig
+  au BufNewFile,BufRead $XDG_CONFIG_HOME/git/config		setf gitconfig
 endif
 au BufNewFile,BufRead git-rebase-todo		setf gitrebase
 au BufRead,BufNewFile .gitsendemail.msg.??????	setf gitsendemail

src/testdir/test_filetype.vim

@@ -171,7 +171,7 @@ let s:filename_checks = {
     \ 'gdmo': ['file.mo', 'file.gdmo'],
     \ 'gedcom': ['file.ged', 'lltxxxxx.txt'],
     \ 'gitcommit': ['COMMIT_EDITMSG', 'MERGE_MSG', 'TAG_EDITMSG'],
-    \ 'gitconfig': ['file.git/config', '.gitconfig', '.gitmodules', 'file.git/modules//config', '/.config/git/config'],
+    \ 'gitconfig': ['file.git/config', '.gitconfig', '.gitmodules', 'file.git/modules//config', '/.config/git/config', '/etc/gitconfig'],
     \ 'gitolite': ['gitolite.conf'],
     \ 'gitrebase': ['git-rebase-todo'],
     \ 'gitsendemail': ['.gitsendemail.msg.xxxxxx'],

src/version.c

@@ -792,6 +792,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    498,
 /**/
     497,
 /**/