FreeBSD: Fix bootstrapping tools under Linux/musl

musl libc has deprecated LFS64 aliases, so bootstrapping FreeBSD tools
under musl distros has been failing with stat64 errors.

Apply the aliases under non-glibc Linux to fix this problem.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Val Packett <val@packett.cool>
Closes #15780