Skip empty parts for stringToEnum template

metaEnum.keyToValue("") will results all flags get set, thus creating a
enum with empty (0) flags become impossible. This patch fixes that.

tests/main.cpp

@@ -32,7 +32,7 @@ template<typename T>
 T stringToEnum(QMetaEnum metaEnum, const QString &str)
 {
     T ret = {};
-    const auto splitted = str.split(QLatin1Char('|'));
+    const auto splitted = str.split(QLatin1Char('|'), Qt::SkipEmptyParts);
     for (const auto &value : splitted) {
         ret |= T(metaEnum.keyToValue(qPrintable(value)));
     }