meta-phosphor: mboxd: add symlink as git

Add a symbolic link to mboxd.bb named _git.bb and sets the
preferred version for the recipe.

Change-Id: I773c2d9ce4694d43103fc5ee076fba627e815a75
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/conf/distro/include/phosphor-defaults.inc b/conf/distro/include/phosphor-defaults.inc
index 79d6c47..72fab7b 100644
--- a/conf/distro/include/phosphor-defaults.inc
+++ b/conf/distro/include/phosphor-defaults.inc
@@ -251,3 +251,4 @@
 PREFERRED_VERSION_phosphor-state-manager = "1.0"
 PREFERRED_VERSION_phosphor-ipmi-host = "1.0"
 PREFERRED_VERSION_phosphor-dbus-monitor = "1.0"
+PREFERRED_VERSION_mboxd = "1.0"
diff --git a/recipes-phosphor/mboxd/mboxd_git.bb b/recipes-phosphor/mboxd/mboxd_git.bb
new file mode 120000
index 0000000..72426c0
--- /dev/null
+++ b/recipes-phosphor/mboxd/mboxd_git.bb
@@ -0,0 +1 @@
+mboxd.bb
\ No newline at end of file