conf/layer.conf: add BBFILES_DYNAMIC and dynamic layers

some recipes under meta-oe have dependency on meta-python,
and test_world of yocto-check-layer will failed with error
like:

ERROR: test_world (common.CommonCheckLayer)
ERROR: Nothing PROVIDES 'python3-pytoml-native' (but
/meta-openembedded/meta-oe/recipes-extended/mozjs/mozjs_60.9.0.bb
DEPENDS on or otherwise requires it). Close matches:
  python3-numpy-native
  python3-pycairo-native
  python3-rpm-native
ERROR: Required build target 'meta-world-pkgdata' has no buildable
providers.
Missing or unbuildable dependency chain was: ['meta-world-pkgdata',
'mozjs', 'python3-pytoml-native']

fix by make these recipes only active when identified layers are
present

Signed-off-by: Changqing Li <changqing.li@windriver.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/conf/layer.conf

@@ -23,6 +23,11 @@ BBFILE_PATTERN_openembedded-layer := "^${LAYERDIR}/"
 
 BBFILE_PRIORITY_openembedded-layer = "6"
 
+# only activates content when identified layers are present,
+# to ensure yocto compatibility check pass
+BBFILES_DYNAMIC += "meta-python:${LAYERDIR}/dynamic-layers/meta-python/recipes-*/*/*.bb \
+"
+
 # This should only be incremented on significant changes that will
 # cause compatibility issues with other layers
 LAYERVERSION_openembedded-layer = "1"