Build Fix: Workaround symbols inclusion from PCH headers

Broken in b128d498b2

Tested with MinGW 8.1
Tested with VisualStudio 2017

Change-Id: I8f43efe43016ea95866ee018ac9a47373a37373b
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/shared/qtcreator_pch.h

@@ -29,14 +29,37 @@
  */
 
 #if defined __cplusplus
-#include <QtGlobal>
+#include <QtCore/qsystemdetection.h>
 
-#ifdef Q_WS_WIN
-# define _POSIX_
-# include <limits.h>
-# undef _POSIX_
+#ifdef Q_OS_WIN
+#define WIN32_LEAN_AND_MEAN
+
+// lib/Utils needs defines for Windows 8
+#ifdef Q_CC_MINGW
+#define WINVER _WIN32_WINNT_WIN8
+#define _WIN32_WINNT _WIN32_WINNT_WIN8
+#endif // Q_CC_MINGW
+#define NOHELP
+#include <qt_windows.h>
+
+#undef DELETE
+#undef IN
+#undef OUT
+#undef ERROR
+#undef ABSOLUTE
+
+//QT_NO_FLOAT16_OPERATORS is used on Visual Studio 2017 (and earlier):
+//when including <QFloat16> and <bitset> in the same translation unit,
+//it would cause a compilation error due to a toolchain bug (see [QTBUG-72073])
+#if _MSC_VER <= 1920
+#define QT_NO_FLOAT16_OPERATORS
 #endif
 
+#define _POSIX_
+#include <limits.h>
+#undef _POSIX_
+#endif // Q_OS_WIN
+
 #include <QtCore>
 
 #if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
@@ -48,7 +71,7 @@ using Qt::dec;
 using Qt::showbase;
 using Qt::hex;
 using Qt::noforcesign;
-#endif
+#endif //QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 
 #include <stdlib.h>
-#endif
+#endif //defined __cplusplus