python-pyqt5, qtwebengine, qtwebkit, qt-kiosk-browser: skip without meta-python2

Neither of these actually builds with python3, skip them when
meta-python2 isn't included until real fix is available.

qtwebkit might not get the support for python3 at all

qtwebengine I have some changes for the initial build, but there
are many more needed as shown in upstream chromium:
https://bugs.chromium.org/p/chromium/issues/detail?id=942720
https://bugs.chromium.org/p/chromium/issues/list?q=label%3AProj-Python3Migration&can=2

python-pyqt5 is already blacklisted because of sip

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

recipes-python/pyqt5/python-pyqt5_5.13.2.bb

@@ -1,6 +1,11 @@
 require python-pyqt5.inc
 
-inherit pythonnative python-dir
+inherit ${@bb.utils.contains("BBFILE_COLLECTIONS", "meta-python2", "pythonnative python-dir", "", d)}
+
+python() {
+    if 'meta-python2' not in d.getVar('BBFILE_COLLECTIONS').split():
+        raise bb.parse.SkipRecipe('Requires meta-python2 to be present.')
+}
 
 DEPENDS += "sip sip-native python"