QAndroidExtras: release mutex earlier in requestPermissionsInternal()

The g_pendingPermissionRequestsMutex protects only the
g_pendingPermissionRequests QHash, so we can drop it immediately after
the QHash::insert() call. In particular, we don't use reference into
the QHash afterwards, and the following runOnAndroidMainThread() call
is internally synchronized, anyway.

Change-Id: I66a0e402e9ed1edb5fd9fec14e85f9371cc4fc36
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>

src/corelib/platform/android/qandroidextras.cpp

@@ -1106,6 +1106,7 @@ requestPermissionsInternal(const QStringList &permissions)
     const int requestCode = nextRequestCode();
     QMutexLocker locker(&g_pendingPermissionRequestsMutex);
     g_pendingPermissionRequests->insert(requestCode, promise);
+    locker.unlock();
 
     QNativeInterface::QAndroidApplication::runOnAndroidMainThread([permissions, requestCode] {
         QJniEnvironment env;