Fix compiling with GCC 11

See: https://bugreports.qt.io/browse/QTBUG-90395.

Upstream commits:
 - Qt 5.15 -- unavailable as open source
 - Qt 6.0: b2af6332ea37e45ab230a7a5d2d278f86d961b83
 - Qt 6.1: 9c56d4da2ff631a8c1c30475bd792f6c86bda53c

--- old/qtbase/src/corelib/global/qendian.h
+++ new/qtbase/src/corelib/global/qendian.h
@@ -44,6 +44,8 @@
 #include <QtCore/qfloat16.h>
 #include <QtCore/qglobal.h>

+#include <limits>
+
 // include stdlib.h and hope that it defines __GLIBC__ for glibc-based systems
 #include <stdlib.h>
 #include <string.h>

--- old/qtbase/src/corelib/tools/qbytearraymatcher.h
+++ new/qtbase/src/corelib/tools/qbytearraymatcher.h
@@ -42,6 +42,8 @@

 #include <QtCore/qbytearray.h>

+#include <limits>
+
 QT_BEGIN_NAMESPACE


--- old/qtbase/src/tools/moc/generator.cpp
+++ new/qtbase/src/tools/moc/generator.cpp
@@ -42,6 +42,7 @@

 #include <math.h>
 #include <stdio.h>
+#include <limits>

 #include <private/qmetaobject_p.h> //for the flags.
 #include <private/qplugin_p.h> //for the flags.