matrix: E2EE as build option

since this is so broken and requires CGO deps, E2EE support is now only
included with "make E2EE=on ...". The option to enable will then appear
in settings.

matrix_nocrypto.go

@@ -0,0 +1,33 @@
+// +build !e2ee
+
+package main
+
+import (
+	"maunium.net/go/mautrix"
+	"maunium.net/go/mautrix/event"
+	"maunium.net/go/mautrix/id"
+)
+
+func MatrixE2EE() bool { return false }
+
+func InitMatrixCrypto(d *MatrixDaemon) (err error) {
+	d.Encryption = false
+	return
+}
+
+func HandleSyncerCrypto(startTime int64, d *MatrixDaemon, syncer *mautrix.DefaultSyncer) {
+	return
+}
+
+func CryptoShutdown(d *MatrixDaemon) {
+	return
+}
+
+func EncryptRoom(d *MatrixDaemon, room *mautrix.RespCreateRoom, userID id.UserID) (encrypted bool) {
+	return
+}
+
+func SendEncrypted(d *MatrixDaemon, content *event.MessageEventContent, roomID id.RoomID) (err error) {
+	err = d.send(content, roomID)
+	return
+}