Re-enable QT_NO_NARROWING_CONVERSIONS_IN_CONNECT for Qt

This define used to be set for the entirety of the Qt build but
was lost during the qmake->CMake transition. Re-enable it.

Change-Id: Idc4cb6ada485158559485b60f62f76439550b255
Pick-to: 6.2
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

cmake/QtInternalTargets.cmake

@@ -131,6 +131,7 @@ if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" AND CMAKE_SYSTEM_NAME STREQUAL "
     target_compile_options(PlatformCommonInternal INTERFACE -Wno-ignored-attributes)
 endif()
 
+target_compile_definitions(PlatformCommonInternal INTERFACE QT_NO_NARROWING_CONVERSIONS_IN_CONNECT)
 target_compile_definitions(PlatformCommonInternal INTERFACE $<$<NOT:$<CONFIG:Debug>>:QT_NO_DEBUG>)
 
 function(qt_internal_apply_bitcode_flags target)

tests/auto/corelib/kernel/qobject/tst_qobject.cpp

@@ -27,6 +27,11 @@
 **
 ****************************************************************************/
 
+// This test actually wants to practice narrowing conditions, so never define this.
+#ifdef QT_NO_NARROWING_CONVERSIONS_IN_CONNECT
+#undef QT_NO_NARROWING_CONVERSIONS_IN_CONNECT
+#endif
+
 #include <QTest>
 #include <QtTest/private/qpropertytesthelper_p.h>
 #include <QStringListModel>