Cross Compilation of qt 5.13.0 for raspberry pi

[Alphy]

Hi,
One of my project I am cross compiling the code done on qt for raspberry pi. I am new to qt and first time I am doing cross compilation. I followed the steps for cross compilation given in the below mentioned link.
https://forum.qt.io/topic/68381/cross-compile-qt-windows-to-raspberry-3. I am getting errors at step12. The below attached image is showing the error when trying run the configuration script at step 12. The error I am getting are given below and also attached the image of the error,
c:/SysGCC/qt-everywhere-src-5.13.0/qtbase/qmake/library/qmakebuiltins.cpp:542:104: error: '_popen' was not declared in this scope
+ QLatin1String(" && ") + args).toLocal8Bit().constData(), QT_POPEN_READ)) {
^
c:/SysGCC/qt-everywhere-src-5.13.0/qtbase/qmake/library/qmakebuiltins.cpp:550:32: error: '_pclose' was not declared in this scope
int ec = QT_PCLOSE(proc);
^
make.exe: *** [qmakebuiltins.o] Error 1

I am new to qt and cross compilation I don't know why that error is coming and how I can solve the issue.
I hope somebody in this forum can help me to solve the issue.
Thank you,
Alphy