Remove unnecessary conditions from FSX code.

* cached_data.c
  (svn_fs_x__rep_chain_length): FSX respositories are always sharded.

* transaction.c
  (shards_spanned): Same.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1636614 13f79535-47bb-0310-9956-ffa450edef68
Sync FSX with FSFS:  Merge assorted fixes and improvements from libsvn_fs_fs
and resolve the usual conflicts with FSX.  The merged revisions are:

r1605633 - remove obsolete race handling between 'hotcopy' and 'pack'
r1616613 - improve config file documentation
r1620930 - reintroduce SVN_FS_FS__USE_LOCK_MUTEX conditional flag
r1622946 - fix rev/pack file open retry after pack
r1623368 - factor out some common code into svn_fs_fs__packed_base_rev()
r1623381 - bump instance ID upon recover
r1623402 - don't use instance IDs as part of the cache keys
r1626246 - fix some compiler warnings
r1627949 - make sure to detect format upgrades before committing
r1628161 - add missing error tracing
r1628393, r1628415 - fix compiler warnings in index.c
r1632908 - fix error leak


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1636627 13f79535-47bb-0310-9956-ffa450edef68
* subversion/libsvn_fs_fs/fs.h
  (SVN_FS_FS__USE_LOCK_MUTEX): Remove outdated reference from docstring.
                               no functional change.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1636629 13f79535-47bb-0310-9956-ffa450edef68
Sync FSX with FSFS:
Block (record-only) merge changes from libsvn_fs_fs that have limited
impact on FSX performance and affect code that is to be rewritten.

r1604414 - default to uncompressed revprops
r1624512 - custom shard size
r1634872 - set revprop pack size default to 4kB

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1636638 13f79535-47bb-0310-9956-ffa450edef68