Revert the "DLD_FLAGS" pollution part of r475483.

It was initially got from ruby23, but recent ruby releases have some
differences in runtime linking, which was not hit by exp-run, and caused
trouble with some ports (e.g. devel/leatherman, sysutils/facter).

PR: 230238
Submitted by: fluffy
Reported by: freebsd@ptty.com
Approved by: fluffy