Remove 1986/stein/stein.orig.c

Since the original program does not compile and more than one of us
fixed it (the judges and me and probably others as well) and the fix is
in stein.c we remove the stein.orig.c.

Updated Makefile so this would not be a problem. Updated README.md to
not refer to make alt.

1986/stein/README.md

@@ -6,8 +6,6 @@ Jan Stein
 
         make all
 
-NOTE: The original entry may be built with "make alt".
-
 Judges' comments:
 
 > NOTE: to avoid problems with news and mail, the single line was split