Add the optional dependency Googletest (aka Gtest) to be compiled by
the build system.
 
* trunk/get-deps.sh (gtest): change gtest dir to libgtest and
  add user information.

* trunk/build/generator/gen_base.py (TargetLinked.add_dependencies): 
  Add .cc extension.

* trunk/gen-make.py (_usage_exit): add gtest flag help info. 

* trunk/Makefile.in(): various entries for gtest flags
 
* trunk/build.conf (install): Add Gtest target.

* trunk/configure.ac (): Add AC_ARG_ENABLE command hook and test
  (build rules): add gtest build rules

* INSTALL (Dependency Overview): add entry for Gtest
  (Dependencies in Detail): add entry for Gtest

* doc/programmer/gtest-guide.txt(): Documentation for Subversion's
  installation of Gtest.

* subversion/bindings/cxxhl/gtests/GtestAcceptance.cpp(): Sample test
  for gtest.

* subversion/bindings/cxxhl/gtests/Makefile(): Makefile for sample
  test for gtest.
  

  


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/gtest_addition@1452120 13f79535-47bb-0310-9956-ffa450edef68