win: default shellxescape, shellxquote to empty

Calling cmd.exe in Windows follows a very different pattern from Vim.
The primary difference is that Vim does a nested call to cmd.exe, e.g.
the following call in Vim

    system('echo a 2>&1')

spawns the following processes

    "C:\Program Files (x86)\Vim\vim80\vimrun" -s C:\Windows\system32\cmd.exe /c (echo a 2^>^&1
        ^>C:\Users\dummy\AppData\Local\Temp\VIoC169.tmp 2^>^&1)
    C:\Windows\system32\cmd.exe /c C:\Windows\system32\cmd.exe /c (echo a 2^>^&1
        ^>C:\Users\dummy\AppData\Local\Temp\VIo3C6C.tmp 2^>^&1)
    C:\Windows\system32\cmd.exe  /c (echo a 2>&1
        >C:\Users\dummy\AppData\Local\Temp\VIo3C6C.tmp 2>&1)

The escaping with ^ is needed because cmd.exe calls itself and needs to
preserve the special metacharacters for the last call. However in nvim
no nested call is made, system('') spawns a single cmd.exe process.
Setting shellxescape to "" disables escaping with ^.

The previous default for shellxquote=( wrapped any command in
parenthesis, in Vim this is more meaningful due to the use of tempfiles
to store the output and redirection (also see &shellquote). There is
a slight benefit in having the default be empty because some expressions
that run in console will not run within parens e.g. due to unbalanced
double quotes

    system('echo "a b')

1 files changed, 1 insertions, 5 deletions

diff --git a/test/functional/terminal/edit_spec.lua b/test/functional/terminal/edit_spec.lua
index f691a58f6c..d2b2d8a60c 100644
--- a/test/functional/terminal/edit_spec.lua
+++ b/test/functional/terminal/edit_spec.lua
@@ -8,7 +8,6 @@ local command = helpers.command
 local meths = helpers.meths
 local clear = helpers.clear
 local eq = helpers.eq
-local iswin = helpers.iswin
 
 describe(':edit term://*', function()
   local get_screen = function(columns, lines)
@@ -46,11 +45,8 @@ describe(':edit term://*', function()
     local bufcontents = {}
     local winheight = curwinmeths.get_height()
     local buf_cont_start = rep_size - sb - winheight + 2
-    local function bufline (i)
-      return (iswin() and '%d: (foobar)' or '%d: foobar'):format(i)
-    end
     for i = buf_cont_start,(rep_size - 1) do
-      bufcontents[#bufcontents + 1] = bufline(i)
+      bufcontents[#bufcontents + 1] = ('%d: foobar'):format(i)
     end
     bufcontents[#bufcontents + 1] = ''
     bufcontents[#bufcontents + 1] = '[Process exited 0]'