Sync'ing FSX with FSFS:
Merge r1532193,1534158,1588651 from /subversion/libsvn_fs_fs into
subversion/libsvn_fs_x. Conflicts were due naming differences between
FSX and FSFS.

These are small, local patches concerning pool handling, consistency
and documentation.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1595603 13f79535-47bb-0310-9956-ffa450edef68