Android: set release flag when signing apk

Currently, signing a package by androiddeployqt automatically implies
the --release option, but there is a fix that removes it from being set
by default. To prepare QtCreator for the upcoming change and not to
change its behavior, we need to manually add the --release option to the
argument list.

Change-Id: I31df1b8252a4444afde95a043848391590f4db82
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/android/androidbuildapkstep.cpp

@@ -611,9 +611,11 @@ bool AndroidBuildApkStep::init()
     QStringList argumentsPasswordConcealed = arguments;
 
     if (m_signPackage) {
-        arguments << "--sign" << m_keystorePath.toString() << m_certificateAlias
+        arguments << "--release"
+                  << "--sign" << m_keystorePath.toString() << m_certificateAlias
                   << "--storepass" << m_keystorePasswd;
-        argumentsPasswordConcealed << "--sign" << "******"
+        argumentsPasswordConcealed << "--release"
+                                   << "--sign" << "******"
                                    << "--storepass" << "******";
         if (!m_certificatePasswd.isEmpty()) {
             arguments << "--keypass" << m_certificatePasswd;