Revert "Revert "build: Generate asm_support_gen.h from the build, validate up-to-date""

This reverts commit 592505c3.

Fix HOST_PREFER_32_BIT=true causing buildbot
to fail with the new asm_support genrule.

Test: SOONG_ALLOW_MISSING_DEPENDENCIES=true HOST_PREFER_32_BIT=true\
      make -j32  build-art-host-tests
Original-Change-Id: I1f0f94914d328c396906583d0732e281c076e69f
Change-Id: Ie08a11fdb9486b697d6cef4cec41b23ff120b205