[mlir] Don't use -z,defs on sanitizer builds

This works around link errors when building the python bindings with
ASAN, since the ASAN run-time doesn't get linked into shared libraries.
The ASAN docs specficially call out -z,defs as a potential issue:
https://clang.llvm.org/docs/AddressSanitizer.html#usage

closes https://github.com/llvm/llvm-project/issues/60565

Reviewed By: stellaraccident, mehdi_amini

Differential Revision: https://reviews.llvm.org/D145956