Summary:
man/Makefile.in is an autotools generated file that we do not need nor
want into the repo.
Without this rule it is not removed properly when you issue the command:
"make maintainer-clean"
Reviewers: billiob
Differential Revision: https://phab.enlightenment.org/D383
Alex-P. Natsios
Jerome Pinot
Boris Faure
Carsten Haitzler
Godfath3r