Ensure that Qt handles the minimum macOS version properly

This patch can be dropped for LLVM Clang 17+, after commit
https://github.com/llvm/llvm-project/commit/c8e2dd8c6f490b68e41fe663b44535a8a21dfeab


--- a/qtbase/src/corelib/global/qsystemdetection.h
+++ b/qtbase/src/corelib/global/qsystemdetection.h
@@ -220,6 +220,9 @@
 #  include <Availability.h>
 #  include <AvailabilityMacros.h>
 #
+#  undef __MAC_OS_X_VERSION_MIN_REQUIRED
+#  define __MAC_OS_X_VERSION_MIN_REQUIRED MAC_OS_X_VERSION_MIN_REQUIRED
+#
 #  ifdef Q_OS_MACOS
 #    if !defined(__MAC_OS_X_VERSION_MIN_REQUIRED) || __MAC_OS_X_VERSION_MIN_REQUIRED < __MAC_10_6
 #       undef __MAC_OS_X_VERSION_MIN_REQUIRED