CBOR: remove QT_X11_DEFINES_FOUND dead code

Amends commit be0f1af3f1829da0d321c12dbd40d5743d3b2eb5 ("CBOR: remove
the X11 True and False for good"), which removed the #define from the
top of the files, but didn't remove the checking of the macro from the
bottom of them.

Change-Id: I92e76842a4117f6feed3fffdac2fcec01367101e
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
(cherry picked from commit 00f3ca950a6cab105c95b53ce2b3b93282abcea8)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/serialization/qcborcommon.h

@@ -118,11 +118,4 @@ QT_END_NAMESPACE
 
 QT_DECL_METATYPE_EXTERN(QCborTag, Q_CORE_EXPORT)
 
-// To avoid changing namespace we need to reinstate defines, even though our .cpp
-// will then have to remove them again.
-#if defined(QT_X11_DEFINES_FOUND)
-#  define True  1
-#  define False 0
-#endif
-
 #endif // QCBORSTREAM_H

src/corelib/serialization/qcborstreamreader.h

@@ -203,9 +203,4 @@ private:
 
 QT_END_NAMESPACE
 
-#if defined(QT_X11_DEFINES_FOUND)
-#  define True  1
-#  define False 0
-#endif
-
 #endif // QCBORSTREAMREADER_H

src/corelib/serialization/qcborstreamwriter.h

@@ -88,9 +88,4 @@ private:
 
 QT_END_NAMESPACE
 
-#if defined(QT_X11_DEFINES_FOUND)
-#  define True  1
-#  define False 0
-#endif
-
 #endif // QCBORSTREAMWRITER_H

src/corelib/serialization/qcborvalue.h

@@ -620,9 +620,4 @@ Q_CORE_EXPORT QDataStream &operator>>(QDataStream &, QCborValue &);
 
 QT_END_NAMESPACE
 
-#if defined(QT_X11_DEFINES_FOUND)
-#  define True  1
-#  define False 0
-#endif
-
 #endif // QCBORVALUE_H