conf/layer.conf: Add OE-Core layer dependency

Declare the core collection dependency in layer.conf so layer tooling
can validate the dependency already documented in the README.

Signed-off-by: Luciano Gomes <luciano.dittgen@ossystems.com.br>

Author: lucianogdittgen

conf/layer.conf

@@ -8,6 +8,7 @@ BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
 BBFILE_COLLECTIONS += "ossystems-base"
 BBFILE_PATTERN_ossystems-base := "^${LAYERDIR}/"
 BBFILE_PRIORITY_ossystems-base = "8"
+LAYERDEPENDS_ossystems-base = "core"
 
 addpylib ${LAYERDIR}/lib ossystems