mdadm: Respect config file location in man

mdadm: Respect config file location in man

Default config file location could differ depending on OS (e.g. Debian family).
This patch takes default config file into consideration when creating mdadm.man
file as well as mdadm.conf.man.

Rename mdadm.conf.5 to mdadm.conf.5.in. Now mdadm.conf.5 is generated automatically.

Signed-off-by: Lukasz Florczak <lukasz.florczak@linux.intel.com>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>