Disable malloc fill in HWASan.

HWASan has a feature to fill malloc() memory with non-zero pattern.
This has found a bug or two in the past, but it also keep causing hard
to debug issues. The main problem is lack of diagnostics - use of
pattern-initialized memory is not an immediate crash. More often than
not it manifests as a subtle change in system behavior.

Having MemorySanitizer on Android would be nice...

This change does not affect any shipping configuration, but improves
stability of testing-only SANITIZE_TARGET=hwaddress build.

Bug: 132803232
Bug: 132652537
Bug: 131438232
Bug: 132810685
Test: SANITIZE_TARGET=hwasan on crosshatch successfully boots in ~100%
      attempt (up from ~99% currently).

Change-Id: I7dcbcdf1b8a5b8556e32690327b32f04879e5db1