Allow LSOF_CCDATE to be overriden by an environment variable

Allow LSOF_CCDATE to be overriden by an environment variable

Last-Update: 2014-09-22

Capturing the current time as part of the build process does not make it
deterministic. By allowing the LSOF_CCDATE to be externally set, the current
time can be removed or preset.

Gbp-Pq: Name preset-ccdate