make -skip work with configure -redo

the handling of -skip happens outside the usual argument handling, so we
need to handle -redo manually as well.

Change-Id: I7dcdf729bd9db2ff2ac8dc08bac71462bf30814b
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

qt.pro

@@ -28,6 +28,8 @@ QT_SKIP_MODULES =
 
 # This is a bit hacky, but a proper implementation is not worth it.
 args = $$QMAKE_EXTRA_ARGS
+contains(args, -redo): \
+    args += $$cat($$OUT_PWD/config.opt, lines)
 for (ever) {
     isEmpty(args): break()
     a = $$take_first(args)