Fix trimming memory from main

mobile/src/main/java/be/mygod/vpnhotspot/App.kt

@@ -20,6 +20,8 @@ import be.mygod.vpnhotspot.net.DhcpWorkaround
 import be.mygod.vpnhotspot.room.AppDatabase
 import be.mygod.vpnhotspot.util.DeviceStorageApp
 import be.mygod.vpnhotspot.util.RootSession
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
 import timber.log.Timber
 import java.util.*
 
@@ -62,7 +64,7 @@ class App : Application() {
 
     override fun onTrimMemory(level: Int) {
         super.onTrimMemory(level)
-        if (level >= TRIM_MEMORY_RUNNING_CRITICAL) RootSession.trimMemory()
+        if (level >= TRIM_MEMORY_RUNNING_CRITICAL) GlobalScope.launch { RootSession.trimMemory() }
     }
 
     lateinit var deviceStorage: Application

mobile/src/main/java/be/mygod/vpnhotspot/util/RootSession.kt

@@ -3,6 +3,7 @@ package be.mygod.vpnhotspot.util
 import android.os.Handler
 import android.os.HandlerThread
 import android.os.Looper
+import androidx.annotation.WorkerThread
 import androidx.core.os.postDelayed
 import com.topjohnwu.superuser.Shell
 import timber.log.Timber
@@ -50,6 +51,7 @@ class RootSession : AutoCloseable {
             return instance.Transaction()
         }
 
+        @WorkerThread
         fun trimMemory() = monitor.withLock {
             val instance = instance ?: return
             instance.haltTimeout()