Disable valgrind 32-bit x86. It does not like SSE.

Rationale:
We got a buildbot failure in ART on host-x86-valgrind after
enabling sse4.2 for hosts (which causes clang to use SSE
that is not recognized by valgrind32).

Bug: 63585550

Test: ./run_build_test_target.py art-gtest-valgrind32 completed.

Change-Id: Ic7ba4d1fd028ef39ddb002fcaa1b023595117cd3