included in everything.

I had to keep the copy in include/ rather than the one in src/ because it's
used by include/core/{window,screen}.h. Doing it the other way around caused
pain and complication.

gtest_add_tests is good for the basic Google Test usage, but its source
based scanning falls short in a couple of areas - namely it requires that
there be no space between TEST* and ( and it also does not work for templated
tests.

compiz_discover_tests builds a small C++ program to parse the output
of --gtest_list_tests and adds those at make-time to the CTestTestfile.cmake
in the current binary directory. This allows us to correctly introspect the test
binary and get /all/ the tests regardless of the source file.

lib/libcompiz_core.so (LP: #919948)
  
We do however want to install the headers. Unfortunately CMake gives you
no way to say install(TARGETS something ARCHIVE DESTINATION null) and it
always wants to install the archive. So we work around this problem with
CMake by removing the archives' INSTALL rules and simply installing the
required headers as part of compiz_core: src/CMakeLists.txt.