Matt Witherspoon

cleans up builds using boost 1.67 on latest xcode only personally tried this when ``` CMake Warning at CMakeLists.txt:180 (message): No database libraries found. Only building WASM files. ```

Replaces `CMAKE_SOURCE_DIR` with `CMAKE_CURRENT_SOURCE_DIR` where appropriate, fixing the build when this repo is included in to a larger build tree (such as being a submodule, for example).