This was reverted in llvm#95435 because it broke Android static hwasan binaries. This reland excludes Android from the logic, as suggested by Vitaly.

Original commit message:
When set to non-zero, the HWASan runtime will map the shadow base at the
specified constant address.

This is particularly useful in conjunction with the existing compiler option
'hwasan-mapping-offset', which bakes a hardcoded constant address into
the instrumentation.