When using ASAN on Clang / Linux, the call to `find_library(... asan ...)`
works against us, as it finds GCC's `libasan.so`. To work with Clang,
we should simply not pass any explicit library, as Clang will figure things
out by itself with the `-fsanitize=xxx` options.
Furthermore, Clang is incompatible with `-fsanitize=object-size`, so that's
now also no longer passed on Linux (mimicking the Apple) configuration.
For the long run, it would be better to rewrite this entire section to
select behaviour on a per-compiler basis, rather than per platform. That's
tracked in #105956
Sybren A. Stüvel