pwrctl: add pgood state switching application

pgood_wait simply blocks until the power state changes to
the requested state.

The intent is for use from a systemd unit similar to nm-online.

Change-Id: Icf1e18f5d47d6eb2fc424b4614fd196ef3dfd6ee
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/op-pwrctl/Makefile b/op-pwrctl/Makefile
index b1188ae..dd11965 100644
--- a/op-pwrctl/Makefile
+++ b/op-pwrctl/Makefile
@@ -1,3 +1,4 @@
 BINS=power_control
+SUBDIRS=pgood_wait
 include ../gdbus.mk
 include ../rules.mk