Avoid new "make distcheck" failure, now that VPATH has GNUmakefile.

Avoid new "make distcheck" failure, now that VPATH has GNUmakefile.

* GNUmakefile: Remove commands to create ".version".
They were unnecessary, and caused creation of a newer .version
file in a VPATH build, which in turn caused creation of updated
man/*.1 files reflecting the newer time stamp on .version.
Those *.1 files were not removed (since they're distributed), and
the fact that they remained after "distclean" triggered the failure.

Signed-off-by: Jim Meyering <meyering@redhat.com>