Address Turbo C warnings

Same case as before, return from main() using return instead of exit().

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>

figlet.c

@@ -2037,5 +2037,5 @@ char *argv[];
   if (outlinelen!=0) {
     printline();
     }
-  exit(0);
+  return 0;
 }