LU-14353 obd: move debug.c to obdecho

LU-14353 obd: move debug.c to obdecho

The code in obdclass/debug.c is only used from obdecho/, so move the
file there and clean it up a little on the way (e.g. spaces to TABs).

Similarly lustre_debug.h contains very little that is used outside of
obdecho.  Move that little (LL_CDEBUG_PAGE()) into lustre_lib.h, and
add the declarations needed for debug.c into echo_internal.h.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ia1bcf3f3e1453130ed1adc75918bdad23eb5b5c7
Reviewed-on: https://review.whamcloud.com/41290
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>