QT添加子工程opmapcontrol.pri时，报错

在pro中添加：
include(libs/opmapcontrol/opmapcontrol_external.pri)
INCLUDEPATH += $$PWD/libs/opmapcontrol
#SUBDIRS+=$$PWD/libs/opmapcontrol
DEPENDPATH += \
libs/utils \
libs/utils/src \
libs/opmapcontrol \
libs/opmapcontrol/src \
libs/opmapcontrol/src/mapwidget

INCLUDEPATH += \
libs/utils \
libs \
libs/opmapcontrol
报错D:\QTPOJECT\opmapcontrol_hm\GCOA_test\libs\opmapcontrol\src\mapwidget\opmapwidget.cpp:-1: error: undefined reference to `_imp___ZN9QGLFormatC1E6QFlagsIN3QGL12FormatOptionEEi'类似问题，

http://blog.csdn.net/hpwzd/article/details/7562539