Focus -Wno-over-aligned to just 32-bit x86 Android.

I've even found the code that's making this happen, just don't know why.
I've added a test to assert that it's safe to assume malloc() is 8-byte aligned.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2662

CQ_INCLUDE_TRYBOTS=master.client.skia.android:Test-Android-Clang-NexusPlayer-CPU-Moorefield-x86-Release-GN_Android-Trybot

Change-Id: If8a2898ab3a77571622eb125c97f676e029b902c
Reviewed-on: https://skia-review.googlesource.com/2662
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
2 files changed