The GPL license speaks of "derivative works". Debian has taken the position that deterministically linking against a library with
LD_PRELOAD does not make your program a derivative work. This allows non-GPL code to link against GPL-d libraries and it goes against the traditional understanding of the difference between the GPL and LGPL, and the view point of the FSF.
You can read more about this here,
Does Debian publish their guidelines for GPL and LGPL use? Do they have a public position on linking against GPLed code being permissible? Or, permissible with