meta-google: 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

Removes warning:
WARNING: No bb files matched BBFILE_PATTERN_google-layer ''

(From meta-google rev: 006860684ec5b429b386a474c799a8ded05a6179)

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I0e13c50b59a38fff89c4e737b27b20df56db1b67
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-google/conf/layer.conf b/meta-google/conf/layer.conf
index b446ef0..bec624e 100644
--- a/meta-google/conf/layer.conf
+++ b/meta-google/conf/layer.conf
@@ -5,6 +5,6 @@
             ${LAYERDIR}/recipes-*/*/*.bbappend"
 
 BBFILE_COLLECTIONS += "google-layer"
-BBFILE_PATTERN_google-layer = ""
+BBFILE_PATTERN_google-layer := "^${LAYERDIR}/"
 LAYERVERSION_google-layer = "1"
 LAYERSERIES_COMPAT_google-layer = "thud warrior"