$ ../configure -platform win32-g++ -shared -release -opensource -confirm-license -xplatform win32-g++ -device-option CROSS_COMPILE=i686-w64-mingw32-
+ cd qtbase
+ /cygdrive/g/QT/qt-everywhere-opensource-src-5.7.1/qtbase/configure -top-level -platform win32-g++ -shared -release -opensource -confirm-license -xplatform win32-g++ -device-option CROSS_COMPILE=i686-w64-mingw32-

This is the Qt Open Source Edition.

You are licensed to use this software under the terms of
the GNU Lesser General Public License (LGPL) versions 3.
You are also licensed to use this software under the terms of
the GNU General Public License (GPL) versions 2.

You have already accepted the terms of the Open Source license.

Preparing build tree...
Creating qmake...
./cygdrive/g/QT/qt-everywhere-opensource-src-5.7.1/qtbase/qmake/library/qmakebuiltins.cpp: In member function 'QByteArray QMakeEvaluator::getCommandOutput(const QString&) const':
/cygdrive/g/QT/qt-everywhere-opensource-src-5.7.1/qtbase/qmake/library/qmakebuiltins.cpp:425:104: error: 'popen' was not declared in this scope
                                + QLatin1String(" && ") + args).toLocal8Bit().constData(), QT_POPEN_READ)) {
                                                                                                        ^
/cygdrive/g/QT/qt-everywhere-opensource-src-5.7.1/qtbase/qmake/library/qmakebuiltins.cpp:433:23: error: 'pclose' was not declared in this scope
         QT_PCLOSE(proc);
                       ^