Add to clean target *.core files

When an error occurs, a core dump file is created. They're annoying,
so with a `make clean` let's remove those.

1 files changed, 1 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 40056c6..03775b9 100644
--- a/Makefile
+++ b/Makefile
@@ -12,4 +12,4 @@ $(PROG): ${OBJ}
 clean:
 	rm -f *.o
 	rm -f $(PROG)
-
+	rm -f *.core