Use original make and options when Makefile runs make.

Also avoid the use of the -C option for non-GNU make.
diff --git a/Makefile.in b/Makefile.in
index e1991b3..2184448 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -360,10 +360,10 @@
 	cp -p $(SRCDIR)zconf.h.in zconf.h
 
 minizip-test: static
-	CFLAGS="$(CFLAGS)" make -C contrib/minizip test
+	cd contrib/minizip && { CFLAGS="$(CFLAGS)" $(MAKE) test ; cd ../.. ; }
 
 minizip-clean:
-	make -C contrib/minizip clean
+	cd contrib/minizip && { $(MAKE) clean ; cd ../.. ; }
 
 mostlyclean: clean
 clean: minizip-clean