build-sys: split man pages and man page links

build-sys: split man pages and man page links

The symlinks are generated by asciidoctor and current dist_man_MANS
depends on order (nan page before man link). This solutions is useless
when execute "make -j". The real solution is to keep man pages in
separate variable and use only this variable evaluate what we need to
generate.

Signed-off-by: Karel Zak <kzak@redhat.com>