patch 9.0.0969: matchparen highlight is not updated when switching buffers

Problem:    Matchparen highlight is not updated when switching buffers.
Solution:   Listen to the BufLeave and the BufWinEnter autocmd events.
            (closes #11626)
diff --git a/src/testdir/dumps/Test_matchparen_clear_highlight_1.dump b/src/testdir/dumps/Test_matchparen_clear_highlight_1.dump
new file mode 100644
index 0000000..1a96275
--- /dev/null
+++ b/src/testdir/dumps/Test_matchparen_clear_highlight_1.dump
@@ -0,0 +1,5 @@
+>(+0&#40ffff15|)| +0&#ffffff0@72
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+| +0#0000000&@56|1|,|1| @10|A|l@1| 
diff --git a/src/testdir/dumps/Test_matchparen_clear_highlight_2.dump b/src/testdir/dumps/Test_matchparen_clear_highlight_2.dump
new file mode 100644
index 0000000..c3f93fa
--- /dev/null
+++ b/src/testdir/dumps/Test_matchparen_clear_highlight_2.dump
@@ -0,0 +1,5 @@
+>a+0&#ffffff0@1| @72
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+| +0#0000000&@56|1|,|1| @10|A|l@1| 
diff --git a/src/testdir/test_display.vim b/src/testdir/test_display.vim
index 4364f03..abf1cd0 100644
--- a/src/testdir/test_display.vim
+++ b/src/testdir/test_display.vim
@@ -237,6 +237,37 @@
   call StopVimInTerminal(buf)
 endfunc
 
+" Test for clearing paren highlight when switching buffers
+func Test_matchparen_clear_highlight()
+  CheckScreendump
+
+  let lines =<< trim END
+    source $VIMRUNTIME/plugin/matchparen.vim
+    set hidden
+    call setline(1, ['()'])
+    normal 0
+
+    func OtherBuffer()
+       enew
+       exe "normal iaa\<Esc>0"
+    endfunc
+  END
+  call writefile(lines, 'XMatchparenClear', 'D')
+  let buf = RunVimInTerminal('-S XMatchparenClear', #{rows: 5})
+  call VerifyScreenDump(buf, 'Test_matchparen_clear_highlight_1', {})
+
+  call term_sendkeys(buf, ":call OtherBuffer()\<CR>:\<Esc>")
+  call VerifyScreenDump(buf, 'Test_matchparen_clear_highlight_2', {})
+
+  call term_sendkeys(buf, "\<C-^>:\<Esc>")
+  call VerifyScreenDump(buf, 'Test_matchparen_clear_highlight_1', {})
+
+  call term_sendkeys(buf, "\<C-^>:\<Esc>")
+  call VerifyScreenDump(buf, 'Test_matchparen_clear_highlight_2', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
 func Test_display_scroll_at_topline()
   CheckScreendump
 
diff --git a/src/version.c b/src/version.c
index f26f91a..78df0d8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    969,
+/**/
     968,
 /**/
     967,