ANDROID: enable LLVM_IAS=1 for clang's integrated assembler for aarch64

Step 8 of:
https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/+/master/BINUTILS_KERNEL_DEPRECATION.md

x86_64 is blocked on AOSP LLVM not yet containing:
Link: https://github.com/llvm/llvm-project/commit/3c2a56a857227b6bc39285747269f02cd7a9dbe5

32b arm is blocked on quite a few different issues:
Link: https://lore.kernel.org/linux-arm-kernel/CAKwvOdndZRv+_FaNFUBtT=zEPG3mh2cb9vfRFCsU5Dus4zzcEw@mail.gmail.com/



Bug: 141693040
Bug: 169938486
Bug: 171348143
Bug: 172699078
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Change-Id: I2d8ca9c8218a2ad96505daa9f029ed5a3bdb3661