Add "spotless" Makefile target

diff --git a/klibc/Makefile b/klibc/Makefile
index ef4ba4b..0eefe8c 100644
--- a/klibc/Makefile
+++ b/klibc/Makefile
@@ -134,3 +134,6 @@
 	rm -f arch/*/*.o arch/*/*.lo arch/*/*.i arch/*/*.s arch/*/*.ls
 	rm -rf syscalls syscalls.dir
 	rm -rf socketcalls socketcalls.dir
+
+spotless: clean
+	find . -name \*~ -not -type d -print0 | xargs -0rt rm -f