[sanitizers] Fixes strndup API behaviour when intercepted by sanitizers

Sanitizers ignore flag allocator_may_return_null=1 in strndup() calls.
When OOM is emulated, this causes to the unexpected crash.

Committed by pgousseau on behalf of "Kostyantyn Melnik, kmnls.kmnls@gmail.com"

Reviewed by: pgousseau

Differential Revision: https://reviews.llvm.org/D126452