Tweak some serf and gmock dependencies to allow building a few more optional
projects on Windows without compilation errors.

* trunk/build.conf
  (libsvn_ra_serf): Remove secur32.lib that belongs on serf.
  (libgmock): Don't handle as shared library.
  (serf): Add zlib and secur32.lib as dependencies.
  (__MORE__): Add svnauth.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1520891 13f79535-47bb-0310-9956-ffa450edef68