pkg/ccn-lite: fix xcompile with cmake on macOS

pkg/ccn-lite/Makefile

@@ -7,8 +7,18 @@ PKG_LICENSE=ISC
 
 export RIOT_CFLAGS = $(CFLAGS) $(INCLUDES)
 
-all: git-download
-	cd $(PKG_BUILDDIR)/src && cmake -DCCNL_RIOT=1 -DRIOT_CFLAGS="$(RIOT_CFLAGS)" -DBUILD_TESTING=OFF . && make
-	cp $(PKG_BUILDDIR)/src/lib/libccnl-riot.a $(BINDIR)/ccn-lite.a
+TOOLCHAIN_FILE=$(PKG_BUILDDIR)/xcompile-toolchain.cmake
+
+all: $(PKG_BUILDDIR)/src/Makefile
+	$(MAKE) -C $(PKG_BUILDDIR)/src && \
+	cp $(PKG_BUILDDIR)/src/lib/libccnl-riot.a ${BINDIR}/ccn-lite.a
+
+$(PKG_BUILDDIR)/src/Makefile: $(TOOLCHAIN_FILE)
+	cd $(PKG_BUILDDIR)/src && \
+	cmake -DCMAKE_TOOLCHAIN_FILE=$(TOOLCHAIN_FILE) \
+		  -DCCNL_RIOT=1 -DRIOT_CFLAGS="${RIOT_CFLAGS}" -DBUILD_TESTING=OFF .
+
+$(TOOLCHAIN_FILE): git-download
+	$(RIOTBASE)/dist/tools/cmake/generate-xcompile-toolchain.sh > $(TOOLCHAIN_FILE)
 
 include $(RIOTBASE)/pkg/pkg.mk