given a system that has no libpq.so installed through packages etc

PGDIR = directory where custom postgresql build is installed

configure using "-qt-sql-psql -I$PGDIR/include -I$PGDIR/include/server -L$PGDIR/lib64 -lpq -lpthread"

building qt 5.7.0 fails with:
make[3]: Entering directory '/home/vugtf/development/64-bit/qt-5.7.0/qtbase/src/widgets'
/home/vugtf/development/64-bit/qt-5.7.0/qtbase/src/widgets/uic_wrapper.sh /home/vugtf/development/qt-everywhere-enterprise-src-5.7.0/qtbase/src/widgets/dialogs/qfiledialog.ui -o .uic/ui_qfiledialog.h
/home/vugtf/development/64-bit/qt-5.7.0/qtbase/bin/uic: error while loading shared libraries: libpq.so.5: cannot open shared object file: No such file or directory
Makefile:1830: recipe for target '.uic/ui_qfiledialog.h' failed
make[3]: *** [.uic/ui_qfiledialog.h] Error 127

building qt 5.6.0 fails earlier, on a moc call in qtbase/src/corelib, the generated commandline has the custom include paths, but not the custom library path

-> libpq.so.5 is available in the lib64 subfolder of $PGDIR
-> installation of a system package that provides libpq.so.5 in /usr/lib64 allows the build to continue

The above mentioned -qt-sql-psql parameters for -I/-L are per the docs (http://doc.qt.io/qt-5/sql-driver.html @ "-L command-line")