Function finalize_precompiled_header

copy dir kphp_out/objs/pch_{flags} inside /tmp/kphp_pch and unlink original finally, a folder inside tmp will contain runtime-headers.h and pch folder contents note, that a .gch file way even not exist, it's okay: just copy full folder (for instance, nocc emits a .nocc-pch file instead of requested .gch) todo it's better to use H2PchTarget::after_run_success() for this todo why do we need /tmp/kph