Improve fix of 1990/tbr

In particular the fix to make it more like the original. There was no
need to have the function prototypes at the top of the file.

I also added a couple -Wno- options to the CSILENCE variable in the
Makefile.

I also added to the Makefile so that make alt will build the alt version
(only functional difference is that there is gets() instead of fgets()).

1990/tbr/tbr.c

@@ -1,4 +1,3 @@
-int e(int x),r(int t,int o);
 #define gets(x)fgets((x),512,stdin)
 #define exit(x) exit((x)),0
 #define D ,close(