hlr: Add hlr sub-directory to master Makefile (for 'make compile' checks)

Change-Id: Idbd8241fc7d217885f65f84e11f9f1ea13adb82e
diff --git a/Makefile b/Makefile
index 3f2230b..3b5995a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-SUBDIRS=bsc bsc-nat bts ggsn_tests gprs_gb lapdm mgw msc selftest sgsn sysinfo
+SUBDIRS=bsc bsc-nat bts ggsn_tests gprs_gb hlr lapdm mgw msc selftest sgsn sysinfo
 
 PARALLEL_MAKE:=-j4