tests: Migrate legacy test argument_count.

src/nvim/testdir/Makefile

@@ -27,7 +27,6 @@ SCRIPTS := test_eval.out                                               \
            test86.out  test87.out  test88.out                          \
            test_listlbr.out                                            \
            test_breakindent.out                                        \
-           test_argument_count.out                                     \
            test_close_count.out                                        \
            test_command_count.out                                      \
 

src/nvim/testdir/test_argument_count.in

@@ -1,46 +0,0 @@
-Tests for :[count]argument! and :[count]argdelete     vim: set ft=vim :
-
-STARTTEST
-:%argd
-:argadd a b c d
-:set hidden
-:let buffers = []
-:augroup TEST
-:au BufEnter * call add(buffers, expand('%:t'))
-:augroup END
-:$argu
-:$-argu
-:-argu
-:1argu
-:+2argu
-:augroup TEST
-:au!
-:augroup END
-:let arglists = []
-:.argd
-:call add(arglists, argv())
-:-argd
-:call add(arglists, argv())
-:$argd
-:call add(arglists, argv())
-:1arga c
-:1arga b
-:$argu
-:$arga x
-:call add(arglists, argv())
-:0arga Y
-:call add(arglists, argv())
-:%argd
-:call add(arglists, argv())
-:arga a b c d e f
-:2,$-argd
-:call add(arglists, argv())
-:e! test.out
-:call append(0, buffers)
-:let lnr = line('$')
-:call append(lnr, map(copy(arglists), 'join(v:val, " ")'))
-:w
-:qa!
-ENDTEST
-
-

src/nvim/testdir/test_argument_count.ok

@@ -1,13 +0,0 @@
-d
-c
-b
-a
-c
-
-a b d
-a d
-a
-a b c x
-Y a b c x
-
-a f