In non-test mode, PRISM and prism-auto both write to stdout, without
prism-auto seeing/processing the output of PRISM. If the output of
prism-auto is piped to another program or to a file, the prism-auto
output is buffered. Then, the output by prism-auto (e.g., printing the
command lines) is not properly synchronized with the output of the
PRISM instances.
So, we flush stdout at appropriate locations.
Additionally, on timeout we prepend a '\n' to ensure that the timeout
message starts at a new line (in particular for the common case of a
timeout during explicit model building, where there is no newline from
PRISM until the model is fully built).