Does not compile with Ninja

[Jussi Pakkanen]

The way dbus-cpp sets up gtest and gmock is broken and does not work with Ninja. To replicate:

bzr branch lp:dbus-cpp
cd dbus-cpp
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=debug -G Ninja ..
ninja

This prints the following error:

ninja: error: 'gmock/libs/gtest/libgtest.a', needed by 'tests/bus_test', missing and no known rule to make it

This happens with both Gcc 4.8 and 4.7.