[sanitizer] Don't run malloc hooks for stacktraces

Usually when we generated stacktraces the process is in error state, so
running hooks may crash the process and prevent meaningfull error report.

Symbolizer, unwinder and pthread are potential source of mallocs.

https://b.corp.google.com/issues/228110771

Reviewed By: kda

Differential Revision: https://reviews.llvm.org/D123566