Remove unused function.

The `get_hg_status()` function has been unused since commit
35eab7a51a in 2018.

vendor/clink.lua

@@ -393,21 +393,6 @@ local function get_git_status()
     return { status = is_status, conflict = conflict_found }
 end
 
----
--- Get the status of working dir
--- @return {bool}
----
-local function get_hg_status()
-    local file = io.popen("hg status -0")
-    for line in file:lines() do
-        file:close()
-        return false
-    end
-    file:close()
-
-    return true
-end
-
 ---
 -- Get the status of working dir
 -- @return {bool}