[experimental] Add sanitizer options to LDC.

Add some of the sanitizer passes to LDC. This is not complete (linking must be
done using clang and the right `-fsanitize=` option) and may not be useful at
all.

If it proves to be usefull then a lot of other options (e.g. blacklist) must be
added.
Merge remote-tracking branch 'origin/master' into merge-2.064
Merge remote-tracking branch 'origin/merge-2.064' into merge-2.064
Revert "Declare more TypeClass instances as builtin."

This reverts commit f7f62a609db70b9db6450c8752858c5c8470b1e3.