remove all *.out files

Makefile

@@ -49,6 +49,11 @@ cleansed : .FORCE
 
 purified : .FORCE
 	rm -rf tests-c/*.out
+	rm -rf tests-cpp/*.out
+	rm -rf tests-err/*.out
+	rm -rf tests-gnu/*.out
+	rm -rf tests-knr/*.out
+	rm -rf tests-std/*.out
 
 spotless : clean tidy cleansed purified