Fix ar-test build when jansson.h requires a flag

This header is not directly necessary for this program, but it is
indirectly included.

Author: flowerysong

CHANGELOG.md

@@ -11,6 +11,7 @@ All notable changes to this project will be documented in this file.
 ### Removed
 
 ### Fixed
+- Build issues on FreeBSD.
 - libopenarc - `arc_free()` accepts NULL.
 - libopenarc - `c` is not a required tag in `ARC-Message-Signature`.
 

Makefile.am

@@ -105,7 +105,7 @@ openarc_ar_test_SOURCES = \
 	util/arc-nametable.c \
 	util/arc-nametable.h
 
-openarc_ar_test_CPPFLAGS = -I$(srcdir)/libopenarc -I$(srcdir)/util
+openarc_ar_test_CPPFLAGS = -I$(srcdir)/libopenarc -I$(srcdir)/util $(LIBJANSSON_CFLAGS)
 endif
 
 $(DIST_ARCHIVES).sha1: $(DIST_ARCHIVES)