editors/tamago: Mark MAKE_JOBS_UNSAFE

Sometimes parallel build fails with such error as following:

egg-com.el:35:11: Error: Loading file /wrkdirs/usr/ports/editors/tamago/work-devel_nox/tamago-4.0.6.0.20041122.19.15/egg-edep.elc failed to provide feature `egg-edep'

PR: 276882
Approved by: maintainer timeout