dca: force gnu89 C standard

Signed-off-by: Felix Paul Kühne <fkuehne@videolan.org>
(cherry picked from commit 3618f40881367d66fa7d961330e6fc6f1e4df683)

contrib/src/dca/rules.mak

@@ -24,7 +24,7 @@ libdca: libdca-$(DCA_VERSION).tar.bz2 .sum-dca
 	$(MOVE)
 
 .dca: libdca
-	cd $< && $(HOSTVARS) ./configure $(HOSTCONF)
+	cd $< && $(HOSTVARS) CFLAGS="$(CFLAGS) -std=gnu89" ./configure $(HOSTCONF)
 	cd $< && $(MAKE) -C include install
 	cd $< && $(MAKE) -C libdca install
 	touch $@