as of autoconf 2.72 neither ac_cv_sys_large_files nor
ac_cv_sys_file_offset_bits are populated. 1b57b62 introduced a
workaround just for ac_cv_sys_file_offset_bits by checking if it's not
empty.
expand fix to cover ac_cv_sys_large_files as well and check
ac_cv_sys_largefile_opts which is populated in autoconf 2.72 [1]
1. https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=cf09f48841b66fe76f606dd6018bb3a93242a7c9
