They are no longer needed, as there were only used by autoconf builds.
For CMake, we either use external googletest, or use CMake download capabilities.

Recent CMake versions throw the following warning when building
googletest 1.8.1. Bumping to 1.11.0 that has a minimum version of 2.8.12
fixes that
```
 CMake Deprecation Warning at build/googletest-src/CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 2.8.12 will be removed from a future version of
  CMake.
```

* Use instead of CMAKE_SOURCE_DIR and CMAKE_BINARY_DIR
* Also PROJECT_SOURCE_DIR and PROJECT_BINARY_DIR, which are similar
* Set properties with a list variable rather than a long line
* Correction to 'proj_test_set_properties' function, rename ENVIRONMENT:
  - PROJ_IGNORE_USER_WRITABLE_DIRECTORY     (ignored)
  - PROJ_SKIP_READ_USER_WRITABLE_DIRECTORY  (used by filemanager.cpp)

This is already what is used by cmake builds

This fixes issues with MinGW when threads are used.

For CMake builds, latest googletest 1.8.0 is downloaded.

Following officially recommended integration for CMake-enabled projects
https://github.com/google/googletest/blob/master/googletest/README.md

  "Use CMake to download GoogleTest as part of the build's configure step.
  This is just a little more complex, but doesn't have the limitations
  of the other methods."

Since, our copy of test/googletest
- is a very minimalist copy of googletest
- does not include any official CMake scripts
- would require copying parts of googletest CMakeLists.txt, compilater/linker flags (e.g. -lpthreads)
for reliable multi-platform builds, it is reasoanable to rely on download
All pros and cons advantages are discussed in teh README.md linked above.

Closes #1033