[Test] Make allocator_sanity.swift more robust on 32-bit.
[Test] Make allocator_sanity.swift more robust on 32-bit.

This test attempts to allocate Int.max bytes and asserts that it crashes. However, this can actually succeed in (some) 32-bit environments, since Int.max is only 2^32-1 bytes there. This causes spurious test failures. Ensure the test crashes by making two gargantuan allocations.

rdar://91687691

atrick/swift,JGiola/swift,gregomni/swift,benlangmuir/swift,apple/swift,benlangmuir/swift,benlangmuir/swift,apple/swift,glessard/swift,gregomni/swift,JGiola/swift,glessard/swift,apple/swift,roambotics/swift,glessard/swift,glessard/swift,roambotics/swift,apple/swift,glessard/swift,JGiola/swift,JGiola/swift,gregomni/swift,benlangmuir/swift,benlangmuir/swift,JGiola/swift,atrick/swift,gregomni/swift,atrick/swift,roambotics/swift,roambotics/swift,atrick/swift,benlangmuir/swift,gregomni/swift,glessard/swift,roambotics/swift,roambotics/swift,ahoppen/swift,ahoppen/swift,ahoppen/swift,apple/swift,ahoppen/swift,atrick/swift,gregomni/swift,ahoppen/swift,apple/swift,JGiola/swift,ahoppen/swift,atrick/swift