[Building] Include defines.pri after Qt modules are added

Fixes regression from 74883f8af4
Closes #1253

src/defines.pri

@@ -36,15 +36,18 @@ mac: DEFINES *= DISABLE_DBUS
 
     isEqual(QT_MAJOR_VERSION, 5) {
         greaterThan(QTWEBKIT_VERSION_MAJOR, 4) {
+            # There is one Qt5WebKitWidgets version now, which has same features as QtWebKit 2.3
             DEFINES *= USE_QTWEBKIT_2_2 USE_QTWEBKIT_2_3
         }
     }
     else { # Qt 4
-        greaterThan(QTWEBKIT_VERSION_MAJOR, 3):greaterThan(QTWEBKIT_VERSION_MINOR, 8) {
+        equals(QTWEBKIT_VERSION_MAJOR, 4):greaterThan(QTWEBKIT_VERSION_MINOR, 8) {
+            # 4.9.x = QtWebKit 2.2
             DEFINES *= USE_QTWEBKIT_2_2
         }
 
-        greaterThan(QTWEBKIT_VERSION_MAJOR, 3):greaterThan(QTWEBKIT_VERSION_MINOR, 9) {
+        equals(QTWEBKIT_VERSION_MAJOR, 4):greaterThan(QTWEBKIT_VERSION_MINOR, 9) {
+            # 4.10.x = QtWebKit 2.3
             DEFINES *= USE_QTWEBKIT_2_3
         }
     }

src/lib/lib.pro

@@ -1,5 +1,3 @@
-include(../defines.pri)
-
 isEqual(QT_MAJOR_VERSION, 5) {
     QT += webkitwidgets network widgets printsupport sql script gui-private
 } else {
@@ -11,6 +9,7 @@ TEMPLATE = lib
 
 DEFINES *= QUPZILLA_SHAREDLIBRARY
 
+include(../defines.pri)
 include(3rdparty/qtsingleapplication.pri)
 include(../../translations/translations.pri)
 include(plugins/qtwebkit/qtwebkit-plugins.pri)