qfloat16: remove the metatype dependency

This macro usage is not correct. I don't know what it is for because the
documentation next to it describes how to use it, not why one should use
it. Anyway, it's most definitely the incorrect solution for whatever
problem there may have been, so remove.

I also couldn't move it to removed_api.cpp. If I do, then the
QMetaTypeInterface created for qfloat16 misses the pointers to
QDataStream. I'm not sure why... I think it's because the operator>> and
operator<< become ambiguous, so the SFINAE to check if they exist gives
up.

Change-Id: I3d74c753055744deb8acfffd17247e1d2317f11c
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

src/corelib/compat/removed_api.cpp

@@ -369,6 +369,7 @@ void QXmlStreamReader::addData(const char *data)
 #endif // QT_CONFIG(xmlstreamreader)
 
 // inlined API
+#include "qfloat16.h"
 #include "qstring.h"
 
 #endif // QT_CORE_REMOVED_SINCE(6, 5)

src/corelib/global/qfloat16.cpp

@@ -7,7 +7,10 @@
 #include <cmath> // for fpclassify()'s return values
 
 #include <QtCore/qdatastream.h>
+#include <QtCore/qmetatype.h>
+#include <QtCore/qtextstream.h>
 
+QT_DECL_METATYPE_EXTERN(qfloat16, Q_CORE_EXPORT)
 QT_BEGIN_NAMESPACE
 
 QT_IMPL_METATYPE_EXTERN(qfloat16)

src/corelib/global/qfloat16.h

@@ -6,7 +6,7 @@
 #define QFLOAT16_H
 
 #include <QtCore/qglobal.h>
-#include <QtCore/qmetatype.h>
+#include <QtCore/qmath.h>
 #include <QtCore/qnamespace.h>
 #include <limits>
 #include <string.h>
@@ -345,8 +345,6 @@ inline auto qHypot(qfloat16 x, qfloat16 y, qfloat16 z)
 
 QT_END_NAMESPACE
 
-QT_DECL_METATYPE_EXTERN(qfloat16, Q_CORE_EXPORT)
-
 namespace std {
 template<>
 class numeric_limits<QT_PREPEND_NAMESPACE(qfloat16)> : public numeric_limits<float>