configure: Print out enabled programs

Better message that ffplay is not going to be built by printing out what
will be built.

Based on a patch by Moritz Barsnick.
Signed-off-by: rogerdpack <rogerpack2005@gmail.com>
Reviewed-by: Ganesh Ajjanagadde <gajjanag@mit.edu>
Signed-off-by: Timothy Gu <timothygu99@gmail.com>

configure

@@ -5958,6 +5958,10 @@ test -n "$random_seed" &&
     echo "random seed               ${random_seed}"
 echo
 
+echo "Enabled programs:"
+print_enabled '' $PROGRAM_LIST | print_3_columns
+echo
+
 echo "External libraries:"
 print_enabled '' $EXTERNAL_LIBRARY_LIST | print_3_columns
 echo