Don't look for unittest support headers that don't exist

Makefile

@@ -452,7 +452,7 @@ test: $(BIN_DIR)/$(EXE) $(LIB_DIR)/libvg.a test/build_graph $(BIN_DIR)/shuf $(BI
 	. ./source_me.sh && doc/test-docs.sh
 	cd test && rm -rf tmp && mkdir tmp && mv 2_2.mat build_graph.cpp default.mat tmp && rm -f *.* && mv tmp/* . && rmdir tmp
 
-docs: $(SRC_DIR)/*.cpp $(SRC_DIR)/*.hpp $(ALGORITHMS_SRC_DIR)/*.cpp $(ALGORITHMS_SRC_DIR)/*.hpp $(SUBCOMMAND_SRC_DIR)/*.cpp $(SUBCOMMAND_SRC_DIR)/*.hpp $(UNITTEST_SRC_DIR)/*.cpp $(UNITTEST_SRC_DIR)/*.hpp $(UNITTEST_SUPPORT_SRC_DIR)/*.cpp $(UNITTEST_SUPPORT_SRC_DIR)/*.hpp
+docs: $(SRC_DIR)/*.cpp $(SRC_DIR)/*.hpp $(ALGORITHMS_SRC_DIR)/*.cpp $(ALGORITHMS_SRC_DIR)/*.hpp $(SUBCOMMAND_SRC_DIR)/*.cpp $(SUBCOMMAND_SRC_DIR)/*.hpp $(UNITTEST_SRC_DIR)/*.cpp $(UNITTEST_SRC_DIR)/*.hpp $(UNITTEST_SUPPORT_SRC_DIR)/*.cpp
 	doxygen
 	echo "View documentation at: file://$(PWD)/doc/doxygen/index.html"