Do not generate calls to the 128-bit function __multi3() on 32-bit ARM

Re-applying this patch after bots failures. Should be fine now.

The function __multi3() is undefined on 32-bit ARM, so a call to it should
never be emitted. Instead, plain instructions need to be generated to
perform 128-bit multiplications.

Differential Revision: https://reviews.llvm.org/D103906