vim-patch:partial:8.1.0822: peeking and flushing output slows down execution

Problem:    Peeking and flushing output slows down execution.
Solution:   Do not update the mode message when global_busy is set.  Do not
            flush when only peeking for a character. (Ken Takata)
cb574f4154

Omit inchar() change: it breaks too many tests.

N/A patches for version.c:

vim-patch:8.2.5170: tiny issues

Problem:    Tiny issues.
Solution:   Tiny improvements.
944cc9ceba

test/functional/vimscript/null_spec.lua

@@ -135,7 +135,7 @@ describe('NULL', function()
     null_test('does not make Neovim crash when v:oldfiles gets assigned to that', ':let v:oldfiles = L|oldfiles', 0)
     null_expr_test('does not make complete() crash or error out',
                    'execute(":normal i\\<C-r>=complete(1, L)[-1]\\n")',
-                   '', '\n', function()
+                   0, '', function()
       eq({''}, curbufmeths.get_lines(0, -1, false))
     end)
     null_expr_test('is accepted by setmatches()', 'setmatches(L)', 0, 0)