Link with $(CXX), not the build host g++.

diff -Nrup a/Makefile b/Makefile
--- a/Makefile	2019-03-23 16:46:05.000000000 +0100
+++ b/Makefile	2026-10-22 17:22:14.180385931 +0200
@@ -37,7 +37,7 @@ zita-dc1:	CPPFLAGS += $(shell pkg-config
 zita-dc1:	LDLIBS += -lclxclient -lclthreads -ljack -lpng -lpthread \
 	-lcairo -lXft -lX11 -lrt
 zita-dc1:	$(ZITA-DC1_O) 
-	g++ $(LDFLAGS) -o $@ $(ZITA-DC1_O) $(LDLIBS)
+	$(CXX) $(LDFLAGS) -o $@ $(ZITA-DC1_O) $(LDLIBS)
 $(ZITA-DC1_O):
 -include $(ZITA-DC1_O:%.o=%.d)