diff -rupN --no-dereference qwt-6.1.4/textengines/mathml/mathml.pro qwt-6.1.4-new/textengines/mathml/mathml.pro
--- qwt-6.1.4/textengines/mathml/mathml.pro	2019-01-02 17:21:31.504466243 +0100
+++ qwt-6.1.4-new/textengines/mathml/mathml.pro	2020-01-06 17:17:19.695623736 +0100
@@ -60,6 +60,8 @@ contains(QWT_CONFIG, QwtPkgConfig) {
 
     QMAKE_PKGCONFIG_LIBDIR = $${QWT_INSTALL_LIBS}
     QMAKE_PKGCONFIG_INCDIR = $${QWT_INSTALL_HEADERS}
+    
+    QMAKE_PKGCONFIG_DESTDIR = pkgconfig
 
     # QMAKE_PKGCONFIG_DESTDIR is buggy, in combination
     # with including pri files: better don't use it