meta-integrity: add sanity check

Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-integrity/classes/sanity-meta-integrity.bbclass

@@ -0,0 +1,10 @@
+addhandler integrity_bbappend_distrocheck
+integrity_bbappend_distrocheck[eventmask] = "bb.event.SanityCheck"
+python integrity_bbappend_distrocheck() {
+    skip_check = e.data.getVar('SKIP_META_INTEGRITY_SANITY_CHECK') == "1"
+    if 'integrity' not in e.data.getVar('DISTRO_FEATURES').split() and not skip_check:
+        bb.warn("You have included the meta-integrity layer, but \
+'integrity' has not been enabled in your DISTRO_FEATURES. Some bbappend files \
+and preferred version setting may not take effect. See the meta-integrity README \
+for details on enabling integrity support.")
+}