Should be a problem of your Qwt installation.

In qwtpolarbuild.pri you find the line "CONFIG += qwt" that adds all Qwt related stuff to your Makefile - as long you have configured qmake to find qwt.prf.
Read the Qt docs how to do it - one possible way is: "qmake -set QMAKEFEATURES ..."

Of course your Qwt installation has to be built the regular way - ended with "make install".

Uwe