minor

Makefile

@@ -173,9 +173,10 @@ test_single: BUILD/test_single
 test_multiple: BUILD/test_multiple
 	@echo "-done target $@"
 
-buildf:
+buildf: BUILD/.
 	@mkdir -p BUILD
 
+
 BUILD/homog2d_test_SYVN BUILD/homog2d_test_SNVN BUILD/homog2d_test_SYVY BUILD/homog2d_test_SNVY: misc/homog2d_test.cpp homog2d.hpp Makefile buildf
 	@if [ -f BUILD/$(notdir $@).stderr ]; then rm BUILD/$(notdir $@).stderr; fi
 	$(CXX) $(CXXFLAGS) -Wno-unused-but-set-variable -O2 -o $@ $< $(LDFLAGS) 2>BUILD/$(notdir $@).stderr