Remove Windows support, for now

Something's wrong with the ports, it's late and I need some rest!

src/rebar3_checkshell_arch.erl

@@ -21,29 +21,20 @@ do({true = _IsMacOS, false = _IsLinux, false = _IsWindows}, Files, State) ->
     execute(darwin, Files, State);
 do({false = _IsMacOS, true = _IsLinux, false = _IsWindows}, Files, State) ->
     execute(linux, Files, State);
-do({false = _IsMacOS, false = _IsLinux, true = _IsWindows}, Files, State) ->
-    execute(windows, Files, State).
+do({false = _IsMacOS, false = _IsLinux, true = _IsWindows}, _Files, _State) ->
+    {error, "checkshell: no support for Windows yet"}.
 
 -spec execute(Arch, Files, State) -> Result when
-    Arch :: darwin | linux | windows,
+    Arch :: darwin | linux,
     Files :: string(),
     Result :: {ok, State} | {error, rebar3_checkshell_utils:str()}.
 execute(Arch, Files, State) ->
     ArchDir = filename:join(rebar3_checkshell_utils:priv_dir(), atom_to_list(Arch) ++ ".x86_64"),
-    Ext = extension_for(Arch),
-    Exec = filename:join(ArchDir, "shellcheck" ++ Ext),
+    Exec = filename:join(ArchDir, "shellcheck"),
     OpenPortCmd = {spawn, Exec ++ args(Files, State)},
     OpenPortOpts = [exit_status],
     result(port_loop(erlang:open_port(OpenPortCmd, OpenPortOpts), ""), State).
 
--spec extension_for(Arch) -> Ext when
-    Arch :: darwin | linux | windows,
-    Ext :: rebar3_checkshell_utils:str().
-extension_for(windows) ->
-    ".exe";
-extension_for(_Other) ->
-    "".
-
 -spec result({ExitCode, Analysis}, State) -> Result when
     ExitCode :: non_neg_integer(),
     Analysis :: string(),