Standardize on the vi editing directives being on the first line.
diff --git a/libbb/last_char_is.c b/libbb/last_char_is.c
index 9bd7099..9bf0bee 100644
--- a/libbb/last_char_is.c
+++ b/libbb/last_char_is.c
@@ -1,3 +1,4 @@
+/* vi: set sw=4 ts=4: */
 /*
  * busybox library eXtended function
  *