meta-romulus: layer.conf: set BBFILE_PATTERN

Bitbake uses this regex to associate recipes and bbappends from BBFILES
(which contains recipes and bbappends from -all- layers listed in
bblayers.conf) to this layer.  The association is then used to map the
BBFILE_PRIORITY value for this layer onto the recipes provided by this
layer.

BBFILE_PRIORITY is used to determine which recipe to use when the same
recipe appears in multiple layers.

Without BBFILE_PATTERN set, recipes in this layer will get a default
priority and not the priority specified in BBFILE_PRIORITY.

This layer doesn't set a priority anyway, so functionally this patch is
a noop but it is an improvement from a correctness standpoint, and it
makes a warning go away:

WARNING: No bb files matched BBFILE_PATTERN_foo-layer

(From meta-ibm rev: 8b843642e36fc9d1ac8921a98dd2710dccf1e514)

Change-Id: I5c6102045f5aaa6146dc1902b106063896d073b8
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-ibm/meta-romulus/conf/layer.conf b/meta-ibm/meta-romulus/conf/layer.conf
index e4859f7..13858d5 100644
--- a/meta-ibm/meta-romulus/conf/layer.conf
+++ b/meta-ibm/meta-romulus/conf/layer.conf
@@ -6,5 +6,5 @@
             ${LAYERDIR}/recipes-*/*/*.bbappend"
 
 BBFILE_COLLECTIONS += "romulus-layer"
-BBFILE_PATTERN_romulus-layer = ""
+BBFILE_PATTERN_romulus-layer := "^${LAYERDIR}/"
 LAYERSERIES_COMPAT_romulus-layer = "thud warrior"