[CMake] out-of-source build and generated files

[Scott Amort]

Alexander Neundorf wrote:
> If you generate files using ADD_CUSTOM_COMMAND(), you should always use full paths for the generated files, i.e. ${CMAKE_CURRENT_BINARY_DIR}/generatedsource.cpp , both in the ADD_CUSTOM_COMMAND() and in the list of source files.

Perfect... that did it.  Thanks Alexander!

Best,
Scott