build: Add disables for control and presence pkgs

Allow granular control of built packages.

Change-Id: Idaded1f149991b1d767f29e0762015f3ba4a0d9d
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/Makefile.am b/Makefile.am
index c3dee8b..9baa62b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -9,4 +9,11 @@
 libfan_la_SOURCES = \
 	utility.cpp
 
-SUBDIRS = . presence control
+SUBDIRS = .
+
+if WANT_PRESENCE
+SUBDIRS += presence
+endif
+if WANT_CONTROL
+SUBDIRS += control
+endif