meta-google: Enable imjournal for gBMC

The default rsyslog.conf uses `imjournal`, so we should enable it by
default to make sure that the config is valid.

Change-Id: Idba361d3a374a88207e7825216f393522647d11d
Signed-off-by: Willy Tu <wltu@google.com>
diff --git a/meta-google/recipes-extended/rsyslog/rsyslog_%.bbappend b/meta-google/recipes-extended/rsyslog/rsyslog_%.bbappend
index df1524c..f81c9d7 100644
--- a/meta-google/recipes-extended/rsyslog/rsyslog_%.bbappend
+++ b/meta-google/recipes-extended/rsyslog/rsyslog_%.bbappend
@@ -3,3 +3,5 @@
 SRC_URI:append:gbmc = " \
   file://rsyslog.conf \
 "
+
+PACKAGECONFIG:append:gbmc = " imjournal"