nfd: Add nfd-dbg package with debug symbols of nfd and other binaries

Change-Id: Ic7b37f6527e4ff34418f31f09cc33b42086f3499
Refs: #11
diff --git a/nfd/debian/rules.precise b/nfd/debian/rules.precise
index 437c89b..7c5503a 100755
--- a/nfd/debian/rules.precise
+++ b/nfd/debian/rules.precise
@@ -36,3 +36,7 @@
 	rm -f docs/*.pyc
 
 override_dh_auto_test:
+
+.PHONY: override_dh_strip
+override_dh_strip:
+	dh_strip --dbg-package=nfd-dbg