LU-3474 mdd: mdd_links_read() to return linkea_init() errors

ASSERTION(ldata->ld_leh != ((void *)0)) can be triggered in
linkea_links_find() due to earlier mdd_links_read() call
missing to return linkea_init() errors and thus preventing
to detect that ld_leh is not populated.
Plus a few error handling fixes to avoid unnecessary msgs
and also prevent early return.

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Change-Id: I35b1076d8eb036dd600e0fda711417634590b9df
Patch-Set: 4
Revert "TOSS-2181 debug: extra info on changelog_kuc_hdr() assertion"

This reverts commit 7f6373a7657dd46f1fe05f58e88221fd817a9ae1.
LU-3587 changelogs: Account for changelog_ext_rec in CR_MAXSIZE

CR_MAXSIZE needs to account for an llog_changelog_rec that actually
contains a changelog_ext_rec structure rather than a changelog_rec.
With out doing so, a file size approaching the Linux kernel NAME_MAX
length that is renamed to a size also close to, or at, NAME_MAX will
exceed CR_MAXSIZE and trip an assertion.

Change-Id: I2d86955efcbd6d0fd28c87026a7720311b4f5598
Signed-off-by: Christopher J. Morrone <morrone2@llnl.gov>