Without the change `:help` command failed to find the help as:
$ rm -rfv ~/.config/vifm/ ~/.vifm
$ vifm
<in vifm>:help
Error detected while processing command line:
E149: Sorry, no help for vifm-app.txt
This happened because `tags` in `doc` directory was empty:
$(top_srcdir)/data/vim/doc/plugin/tags: \
$(top_srcdir)/data/vim/doc/plugin/vifm-plugin.txt
$(AM_V_GEN)mkdir -p ../data/vim/doc/plugin/; \
if [ -n "$(PERL)" ]; then \
$(srcdir)/helpztags "$(top_srcdir)/data/vim/doc/plugin"; \
elif [ -n "$(VIM)" ]; then \
vim -e -s -c 'helptags $(top_srcdir)/data/vim/doc/plugin|q'; \
else \
touch $@; \
fi
The change pulls in `perl` into build depends to get tags working.