system: make xcb internal

This package is hauntingly ugly. Move this to internal until it is removed or replaced.

Signed-off-by: Ophestra <cat@gensokyo.uk>

system/internal/xcb/export.go

@@ -0,0 +1,22 @@
+// Package xcb implements X11 ChangeHosts via libxcb.
+package xcb
+
+import (
+	"errors"
+)
+
+var ErrChangeHosts = errors.New("xcb_change_hosts() failed")
+
+func ChangeHosts(mode HostMode, family Family, address string) error {
+	var conn *connection
+
+	if c, err := connect(); err != nil {
+		c.disconnect()
+		return err
+	} else {
+		defer c.disconnect()
+		conn = c
+	}
+
+	return conn.changeHostsChecked(mode, family, address)
+}