Update subversion package to 1.6.15.
Also update subversion-base, ap2-subversion, p5-subversion, py-subversion
and ruby-subversion.

Version 1.6.15
(26 Nov 2010, from /branches/1.6.x)
http://svn.apache.org/repos/asf/subversion/tags/1.6.15

  User-visible changes:
  * improve svnsync handling of dir copies (r962377, -8)
  * hide unreadable dirs in mod_dav_svn's GET response (r996884)
  * make 'svnmucc propsetf' actually work (r1005446)
  * limit memory fragmentation in svnserve (r1022675)
  * fix 'svn export' regression from 1.6.13 (r1032970)
  * fix 'svn export' mistakenly uri-encodes paths (issue #3745)
  * fix server-side memory leaks triggered by 'blame -g' (r1032808)
  * prevent crash in mod_dav_svn when using SVNParentPath (r1033166)
  * allow 'log -g' to continue in the face of invalid mergeinfo (r1028108)
  * filter unreadable paths for 'svn ls' and 'svn co' (r997026, -070, -474)
  * fix abort in 'svn blame -g' (issue #3666)
  * fix file handle leak in ruby bindings (issue #3512)
  * remove check for 1.7-style working copies (issue #3729)

  Developer-visible changes:
  * improve some swig parameter mapping (r984565, r1035745)
  * improve test accuracy over dav (r991534, r877814)
  * create fails.log for test runs (r964349)
  * improve detection of 'svnversion' when buildling (r877219, et al)
  * don't violate API layering in dumpstream logic (issue #3733)
  * don't report working copy installs as switched (r1033921)

Version 1.6.14
(Not released, see changes for 1.6.15.)

(taca)