Merge revisions 1533539,-43 from "log addressing" branch intro /trunk
and undo format7-specific changes.

This patch introduces SVN__LINE_CHUNK_SIZE as a global constant instead
of being local to stream.c.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1546700 13f79535-47bb-0310-9956-ffa450edef68