Merge pull request #69 from hzeller/use-design-top

In tests: Use $::env(DESIGN_TOP) where it isn't already.
diff --git a/Makefile_plugin.common b/Makefile_plugin.common
index 4289bd6..06f2c61 100644
--- a/Makefile_plugin.common
+++ b/Makefile_plugin.common
@@ -48,8 +48,7 @@
 	$(CXX) $(CXXFLAGS) $(LDFLAGS) -shared -o $@ $^ $(LDLIBS)
 
 install_plugin: $(NAME).so
-	mkdir -p $(PLUGINS_DIR)
-	cp $< $(PLUGINS_DIR)/$<
+	install -D $< $(PLUGINS_DIR)/$<
 
 test:
 	$(MAKE) -C tests all
diff --git a/xdc-plugin/Makefile b/xdc-plugin/Makefile
index bd454a1..0ca7ba3 100644
--- a/xdc-plugin/Makefile
+++ b/xdc-plugin/Makefile
@@ -4,7 +4,6 @@
 VERILOG_MODULES = BANK.v
 
 install_modules: $(VERILOG_MODULES)
-	mkdir -p $(PLUGINS_DIR)/fasm_extra_modules/
-	cp $< $(PLUGINS_DIR)/fasm_extra_modules/$<
+	install -D $< $(PLUGINS_DIR)/fasm_extra_modules/$<
 
 install: install_modules