Linux executables linked through the clang driver with its default linker,
GNU ld. lld links the same objects in about half the time.
- Native and Node-hosted Linux exe links pass -fuse-ld=lld when ld.lld is
beside the driver's executable (where clang looks first) or on PATH, and
the default driver is in use (no SCRIPTC_LINKER, no sanitizer link).
- A link with lld that fails runs again with the driver's default linker,
whose error is the one reported when that fails too.