patch 9.1.0769: filetype: MLIR files are not recognized

Problem:  filetype: MLIR files are not recognized
Solution: Detect '*.mlir' files as mlir filetype,
          include a mlir filetype plugin
          (Wu, Zhenyu)

closes: #15826

Signed-off-by: Wu, Zhenyu <wuzhenyu@ustc.edu>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index 7f39625..4b5577a 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -576,6 +576,9 @@
 " LyRiCs
 au BufNewFile,BufRead *.lrc			setf lyrics
 
+" MLIR
+au BufNewFile,BufRead *.mlir			setf mlir
+
 " Modula-3 configuration language (must be before *.cfg and *makefile)
 au BufNewFile,BufRead *.quake,cm3.cfg		setf m3quake
 au BufNewFile,BufRead m3makefile,m3overrides	setf m3build
diff --git a/runtime/ftplugin/mlir.vim b/runtime/ftplugin/mlir.vim
new file mode 100644
index 0000000..c6a9dc3
--- /dev/null
+++ b/runtime/ftplugin/mlir.vim
@@ -0,0 +1,10 @@
+" Vim filetype plugin file
+" Language:	MLIR
+
+if exists("b:did_ftplugin") | finish | endif
+let b:did_ftplugin = 1
+
+setl comments=:///,://
+setl commentstring=//\ %s
+
+let b:undo_ftplugin = "setl commentstring< comments<"