Tests: Fix compile

Amends 47bcb63854.

Change-Id: I34a867b3b0b868933937e37e8268b98078aa3023
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

tests/auto/utils/qtcprocess/tst_qtcprocess.cpp

@@ -1233,6 +1233,8 @@ enum class BlockType {
     EventLoop
 };
 
+Q_DECLARE_METATYPE(BlockType)
+
 void tst_QtcProcess::KillBlockingProcess::main()
 {
     std::cout << "Blocking process successfully executed." << std::endl;