Update to upstrea version 2.5.6.
Update to upstrea version 2.5.6.

Detect IO errors properly.
Write #line directives to the correct output stream.

Obtained from:	http://dotat.at/prog/unifdef

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase