Configure to use libappimageupdate

lib/lib.pri

 include($${PWD}/qtlib/qtlib.pri)
+
+unix:!ios:!android {
+    INCLUDEPATH += $${PWD}/AppImageUpdate/include
+
+    DEPENDPATH += $${PWD}/AppImageUpdate/include
+
+    LIBS += \
+        -L$${PWD}/AppImageUpdate-prebuilt/src/ -lappimageupdate \
+        -L$${PWD}/AppImageUpdate-prebuilt/lib/zsync2/src/ -lzsync2 \
+        -L$${PWD}/AppImageUpdate-prebuilt/lib/ -lcpr \
+        -L$${PWD}/AppImageUpdate-prebuilt/lib/zsync2/lib/zlib/ -lz \
+        -L$${PWD}/AppImageUpdate-prebuilt/lib/zsync2/lib/libzsync/ -lzsync \
+        -L$${PWD}/AppImageUpdate-prebuilt/lib/zsync2/lib/librcksum/ -lrcksum
+
+    PRE_TARGETDEPS += \
+        $${PWD}/AppImageUpdate-prebuilt/src/libappimageupdate.a \
+        $${PWD}/AppImageUpdate-prebuilt/lib/zsync2/src/libzsync2.a \
+        $${PWD}/AppImageUpdate-prebuilt/lib/libcpr.a \
+        $${PWD}/AppImageUpdate-prebuilt/lib/zsync2/lib/zlib/libz.a \
+        $${PWD}/AppImageUpdate-prebuilt/lib/zsync2/lib/libzsync/libzsync.a \
+        $${PWD}/AppImageUpdate-prebuilt/lib/zsync2/lib/librcksum/librcksum.a
+
+    LIBS += -L$${PWD}/AppImageUpdate-prebuilt/lib/ -lcurl
+}