- update clean to recurse all build directories and use build system clean
- git clean is used to remove submodule generated build artifacts that
are left in the source tree
- distclean now discards all build directories and any gitignored
filess that were generated in source directories (but not top level)
@find"$(SRC_DIR)/build" -mindepth 1 -maxdepth 1 -type d -exec sh -c "echo {}; cmake --build {} -- clean || rm -rf {}"\;# use generated build system to clean, wipe build directory if it fails
@git submodule foreach git clean -df
@git submodule foreach git clean -dX --force # some submodules generate build artifacts in source