Fix tst_QImageReader::saveColorSpace

After comparing colorspaces was remove from QImage equality, the test
was no longer testing what it was supposed to.

Change-Id: Ie7ee8ac2f488ea4254086cbb91a2662dc729e80b
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

tests/auto/gui/image/qimagereader/tst_qimagereader.cpp

@@ -1913,6 +1913,7 @@ void tst_QImageReader::saveColorSpace()
     QImage stored = QImage::fromData(buf.buffer(), "png");
 
     QCOMPARE(stored, orig);
+    QCOMPARE(stored.colorSpace(), orig.colorSpace());
 }
 
 void tst_QImageReader::readText_data()