stats.lua: don't disable terminal escape sequences on windows

When stats.lua is used without a video window then it uses the terminal.
On Windows, however, so far it disabled ansi escape sequences and used
plaintext unless ANSICON env is set.

It's unclear why it's disabled on windows, because at the time it was
added it only used bold by default and mpv ansi emulation on windows
already supported bold at that time.

We can guess that it was disabled because if the same config is used on
both linux and Windows, and it had complex escape sequences for
stats.lue, then it would be emulated incorrectly on Windows.

This shouldn't be an issue anymore, as the last two commits both enhance
the emulation to be quite complete (and graceful where it's not), and
also enable the much-more complete native VT terminal when possible
(Windows 10).

Just remove this windows exception at stats.lua.

player/lua/stats.lua

@@ -176,17 +176,6 @@ local function has_vo_window()
 end
 
 
-local function has_ansi()
-    local is_windows = type(package) == 'table'
-        and type(package.config) == 'string'
-        and package.config:sub(1, 1) == '\\'
-    if is_windows then
-        return os.getenv("ANSICON")
-    end
-    return true
-end
-
-
 -- Generate a graph from the given values.
 -- Returns an ASS formatted vector drawing as string.
 --
@@ -608,17 +597,10 @@ local function eval_ass_formatting()
         o.nl = o.no_ass_nl
         o.indent = o.no_ass_indent
         o.prefix_sep = o.no_ass_prefix_sep
-        if not has_ansi() then
-            o.b1 = ""
-            o.b0 = ""
-            o.it1 = ""
-            o.it0 = ""
-        else
-            o.b1 = o.no_ass_b1
-            o.b0 = o.no_ass_b0
-            o.it1 = o.no_ass_it1
-            o.it0 = o.no_ass_it0
-        end
+        o.b1 = o.no_ass_b1
+        o.b0 = o.no_ass_b0
+        o.it1 = o.no_ass_it1
+        o.it0 = o.no_ass_it0
     end
 end